EFFECTIVENESS OF SOIL CONSERVATION TO EROSION CONTROL ON SEVERAL TYPE OF LAND USE

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EFFECTIVENESS OF SOIL CONSERVATION TO EROSION CONTROL ON SEVERAL TYPE OF LAND USE

Halus Satriawan1*_{, Erwin Masrul Harahap}2_{, Rahmawaty}3_{, Abubakar Karim}4 1_{Almuslim University, Aceh}

2,3_{Sumatera Utara University, North Sumatera} 4_{Syiah Kuala University, Aceh}

The erosion plot method for direct evaluation in agriculture became necessary to (1) quantify soil erosion on cocoa, areca and oil palm, (2) to determine the most effective soil conservation,

and (3) calculate nutrient content in sediment. The experiment was treated with three conservation practices and the conventional treatment as control in a completely randomized randomised block design. The results showed for the Areca areca land use, that soil conservation with ridges + maize produces the lowest erosion (1.68 t/ha). For cocoa land use, the ridges + groundnut treatment produced the lowest erosion (8.2 t/ha). For oil palm land use, the cover crop of Mucuna bracteata DChad lowest erosion yield (12.2 t/ha). Soil conservation

techniques significantly affected the levels of organic C and available P under the cocoa land use, where ridges + maize hashave the lowest content of organic C and available P in soil sediment (1.03% and 0.69 ppm). Soil conservation at Areca areca land use also has a significant effect on the levels of organic C and available N, but it did not affect significantly the levels of available P and exchangeable K sediments, where ridges + groundnut has have lowest organic C and available N in sediment (1.4% and 0.18%). Furthermore, soil conservation on the land use of oil palm showed a significant effect on the levels of available P, but did not significantly affect on the levels of organic C, available N and exchangeable K sediments. Soil conservation with cover crops Mucuna bracteata DC contains showed the available P lowest available P in sediments (0.86 ppm).

Key words: land use, nutrient, sediment, soilerosion, soil conservation

Halus Satriawan, Lecturer (*Corresponding author), Agrotechnology Department, Faculty of Agriculture, Almuslim University, Almuslim St Matangglumpangdua, Aceh, Indonesia, Post Code 24261, Phone/Fax (+62) 0644-442166. E-mail: satriawan_80@yahoo.co.id

Erwin Masrul Harahap, Professor, Agricultural Science, Sumatera Utara University, Indonesia Rahmawaty, Senior Lecturer, Forestry Department, Sumatera Utara University, Indonesia Abubakar Karim, Professor, Soil Science Department, Syiah Kuala University, Aceh, Indonesia

Formatted: English (United Kingdom), Check spelling and grammar

Formatted: English (United Kingdom)

Commented [SVS1]: AQ: Please spell out DC.

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The loss of soil from land surfaces by erosion is widespread globally and adversely affects

the productivity of all natural ecosystems as well asand agricultural ecosystem (Pimentel 2006).

Loss of soil through erosion also brings with it nutrients contained in the soil. Nutrients loss

due to surface runoff and soil erosion carried away from agricultural land is the main cause of

soil degradation of agriculture land (Bertol et al. 2003). Nitrogen, phosphorus, organic carbon,

potassium, calcium, magnesium and sodium are the main nutrients carried by overland flow

and soil erosion (Hidayat et al. 2012).

Krueng Sieumpo watershed is the sub-watershed of Krueng Peusangan Watershed in Aceh

Province, Indonesia, which was categorized categorised as a critical area under unappropriate

land management. In needs rehabilitation (Fitri 2011). The farmers in this area still do not use

their land in accordance with land capability and land suitability. No conservation techniques

are implemented, the cropping patterns and farming practices are inappropriate (Satriawan et

al. 2014). Oil palm (Elaeis guineensis Jacq.), Areca areca (Areca catechu L.) and Cocoa cocoa

(Theobrema cacao L.) are major crops in Kreueng Sieumpo watershed, which spread more

dominant on land with slopes between 9%‒ and 45%. The land area for oil palm plantations in Krueng Sieumpo watershed have has increased rapidly, with 4,644 ha of cultivation under 5

years since 2008 (BKPM 2013). But today, oil palm cultivation is limited to marginal areas

such as hilly sloping lands where they comprise about 60% of the marginal land areas

(Satriawan & Fuady 2012). Similarly to oil palm, Cocoa is one of the major export commodities

in Indonesia. The area under cocoa plantation in Bireuen District in 2012 is 6,023 ha and it still

continues to growing with an average productivity of 0.63 t/ha (BKPM 2013). Areca is also the

main crop of traditional plantation with 7,782 ha of cultivation area and the productivity of 1.5

t/ha of dry beans. As a result of land use patterns, the predicted rate of soil erosion on cultivated

land reaches from 54.6 to 1,007.6 t/ha/year (Satriawan & Harahap 2013), is still higher than the

tolerable erosion in this region ranging from 25.1 to 40 t/ha/year (Fitri 2010).

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The aims of soil conservation for growing more production can be achieved by using land in

accordance with its capabilities, to apply measures to restore the productivity of the soil where

it has been damaged and to prevent further damage from taking place, and to combine sound

methods of soil management with other methods and inputs of modern agriculture to obtain

satisfactory production on sustainable basis (Hudson 1993).

Numerous studies have evaluated the environmental pollution by nutrients currently used in

agriculture (Sharpley & Smith 1990; Pratap Narain et al. 1998; Thomas et al. 1999; Jae-Young

Cho & Kwang-Wan Han 2002; Zuazo et al. 2011). The erosion plot method for direct

evaluation in the field is the most effective to quantify water erosion (Sanchez et al. 2002).

Therefore, it became necessary to quantify soil erosion more extensively, with the aim of

providing a tool for planning soil conservation strategies for many land use types on watershed

basis. The objectives of this study were to determine: (1) the rate of runoff and erosion on each

types of land use, (2) nutrient contents in eroded soil, and (3) the most effective soil

conservation.

MATERIAL AND METHODS

Study Area

The study experimental plot used to measure the overland flow, sediment and nutrient loss

were was located at Krueng Sieumpo watershed (5o_{4′37.65′′ N and 96}o_{45′44.91′′}

E). Three crops were tested: Arecaareca, Cocoa cocoa and Oil oil Palm palm a specific soil

conservation techniques. The experiment lasted for one year (June 2013‒–July 2014). The area was cultivated with 2 years old oil palm trees, 5 years old areca trees and 3 years old Cocoa.

Average annual rainfall in this area was 1.818 mm, and the daily mean air temperature was

27.6°_{C. The soil of the experimental area is classified as Typic Paleudults} _{(USDA Soil}

Taxonomy), which has sandy clay in the topsoil (0‒15 cm depth).

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Experimental Design

The field experiment layout has a completely randomized randomised block design with

three replicas. Four treatments were tested for each land use (three conservation practices and

the conventional treatment as control). The conservation practices were not the same for each

land use type. For areca trees it was: (1) control (no soil conservation); (2) ridges + green beans;

(3) ridges + groundnut; (4) ridges + maize. For cocoa (1) control (no soil conservation); (2)

ridges + green beans; (3) ridges + groundnut; (4) ridges + maize. For oil (1) control (no soil

conservation); (2) green beans; (3) Mucuna bracteata DC.; (4) sediment trap + maize.

The erosion plots were located on the hill slopes of 25% (15o_{) inclination, with an acreage of}

20 m2_{(4 × 5 m) in}_{Cocoa cocoa}_and_{Areca areca}_{area (Figure}_s_{2 and 3), and 80 m}2_{(4 × 20 m)}

in oil palm area (Figure 4). Each erosion plot consisted of a galvanized galvanised enclosure,

drawer collector, sediment and runoff collector (ϴ 0.6 m, 0.8 m high). The application rate of

chemical fertilizer fertiliser during the study was (150 kg N/ha, 100 kg P/ha, and 75 kg K/ha)

for each treatment.

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Ridges are constructed of two pieces with 20 cm high and 25 cm width (Figure 1).

Measurement of runoff and erosion was conducted for each rainfall event during the period of

the experiment. Erosion measurements involved the measurement of the runoff volume and the

measurement of eroded soil. The weight of soil sediment was measured by filtering the water

samples using filter paper. The soil left on the filter paper was dried in an oven at 60 ° C until

the sediment weight became constant. The amount of sediment (E) is calculated using the

following equation:

A x V x C

E ap ap

3 10 

where:

E ‒ eroded soil [t/ha],

Cap ‒ concentration of sediment load [kg/m3],

Vap ‒ volume of runoff [m3],

A ‒ wide area [ha],

10-3 _{‒ unit conversion kg to ton.}

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Figure 3. Experiment plot on Arecaareca

Sediment analysis conducted to measure the content of organic C (Ctot) (Walkley-Black

method), total Nitrogen (Ntot) (Kjeldahl method), P2O5 available (Bray-1 method) and K2O

(extraction with 1 N NH4OAc pH 7.0). The yield of organic C, available N, available P and

exchangeable K carried by runoff was calculated by the equation:

X = Y x E

where:

X ‒ is the total nutrient loss (organic C, available N, available P and exchangeable K) [kg/ha], Y ‒ is the concentration of organic C [%], total nitrogen [%], available P [µg/g] and exchangeable, K [cmol/kg] in sediment,

E ‒ is the total of eroded soil [t/ha].

The amount of runoff and erosion and the data nutrient loss obtained from erosion sediment

were was subjected to ANOVA procedure, and means separation test was done by protected

Least Significant Difference (LSD) test at 5% level of significance.

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Figure 4. Experiment plot on oil palm

RESULTS AND DISCUSSION

Runoff and Soil Erosion

Soil conservation techniques tested on the 3 three investigated land use types had a small

effect on the runoff, but they had significant effects soil erosion rate (Table 1).

Table 1. Runoff and soil erosion on three types of land use

Land use

Treatment Cocoa Runoff Areca Treatments Oil Palm [m3_/ha] Erosion _[t/ha] Runoff _[m3_/ha] Erosion _[t/ha] Runoff _[m3_/ha] Erosion _[t/ha]

Ridges +

green beans 243.22 17.86b 243.00 6.99b Green beans 200.18 18.66b

Ridges +

maize 231.79 27.39

c _{224.00 4.64}a Mucuna _bracteata

DC. 199.50 12.20

In the same column, values with different indices are significantly different from one another at the LSD (P ≤ 0.05) test.

Table 1 presents all runoff events monitored during the experiment. The runoff fluxes from

tested treatments ranged from 210.18 to 243.22 m3_{/ha for cocoa land use, 207.00 to 243.00}

m3_{/ha for areca land use, 199.50 to 238.95 m}3_{/ha for oil palm treatment. For cocoa land use, the}

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soil conservation with ridges + groundnut consistently produced the lowest erosion as compared

to three other methods (8.20 t/ha) and as compared to the control treatment, the erosion under

ridges + groundnut decreased by 79.61%. Then, on the areca land use, the implementation of

ridges maize treatment shows a high ability for controlling the erosion (4.64 t/ha), slightly

better than ridges + green beans treatment, but it is much more effective than groundnut + ridges

and control, decrease by 76.47%. While at oil palm land use, the Mucuna bracteata DC.

treatment was most effectively controlling the erosion (12.20 t/ha), followed by ridges + maize

treatment (12.33 t/ha). Two other treatments (green beans and control) resulted in greater

erosion. As compared to the control treatment, the erosion under Mucuna bracteata DC.

decreased by 34.61%.

The results showed that the intercropping combined with ridges is quite effective to reduce

erosion and runoff at cocoa and areca land use. Ridges modified the soil surface to become

more rugged and served as a water collector. Similarly, a denser plant cover and stratified

canopy on intercropping systems reduced the rain erosivity through interception, and increase

of infiltration due to the diversity of plant root systems. Intercropping system also reduces the

susceptibility for erosion through its extensive root system, which helps to hold soil in place.

In contrary the runoff and erosion at control treatment was were lower as compared to ridges +

maize and ridges + green beans treatment. At the control treatment, runoff during rain have has

no barrier, so that the movement of runoff could transport soil particles. The results of this study

are consistent with the study of Noeralam et al. (2003) who reported that the application of

ridges with canal effectively reduced the overland flow/runoff by 50.8%. Similarly, Fuady and

Satriawan (2011) report 63.5% reduction and erosion to 67.5% (both in the period of vegetative

and generative). Moreover, the results indicated that the beneficial in controlling soil erosion,

similar to other previous studies by Gomez et al. (2009) who reported using cover crop with

barley, reduced the soil losses to 0.8 t/ha/year and the average annual runoff coefficient to 1.2%,

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that indicated the use of a cover crop can be a simple, feasible soil and water conservation

practice.

In the application of soil conservation in oil palm land use, treatment of Mucuna bracteata

DC., maize + sediment trap among oil palm trees shows significantly different erosions between

control and green beans treatment. The use of cover crops such as Mucuna bracteata DC. can

reduce the rate of runoff and erosion through the increased volume of water infiltration, the

improvement of soil physical properties and reduction of high rainfall impact. High rainfall

cause intensive detachment of soil particles, so the soil becomes easily eroded, but alley

cropping, fertilization fertilisation and mulching can reduce soil erosion to tolerable level (Noer

2011). Probable mechanisms for the greater sediment reduction in this study are linked with

changes in flow dynamics through at least three processes. First, the vegetative barrier and

ridges may intercept concentrated flow by decreasing velocity and dispersing runoff; second,

increased ponding may promote the deposition of sediment; third, the ponding may absorb

runoff energy that would cause soil detachment and transport and thus reduce the erosion and

transport capacity.

Nutrient Loss

Soil conservation also affects the nutrient loss together with the sediment. Tables 2, 3 and 4

show for each land use different effects of soil conservation on the levels of organic C, total N,

available P and exchangeable K. Soil conservation techniques can reduce the erosion rates as

well as the amount of organic C and nutrients carried by runoff.

Cocoa

Soil conservation techniques have significantly affected to the levels of organic C and

available P for the cocoa land use but the levels of total N and exchangeable K did not differ.

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Ridges + maize treatment showed lowest content of organic C and available P in soil sediment

(1.03% and 0.69 µg/g) (Table 2). But in contrast to the total weight of nutrients (kg/ha), all

parameters showed a difference to the control treatment.

Table 2. Nutrient content of sediments as a result of the application of soil conservation techniques on Cocoa land use

Means in the same column, marked by indices, are significantly different, based on the LSD (P

≤ 0.05)

The nutrient content in sediment is shows linear correlation with the amount of eroded soil.

In this study the lowest erosion was recorded for ridges + groundnut treatment. These results

indicate that the characteristics of the plant such as the type of plants, roots, and the period of

growth has effect on erosion. Maize is most effective to prevent loss of nutrients through

intensive nutrient absorption mechanism by roots, thus means selectivity of erosion by the

maize is better than the other plants. In addition, ridges helps to inhibit surface flow and

supports the deposition of particles carried by runoff.

Areca

Soil conservation on Areca areca land use has also significant effect on the levels of organic

C and Ntot, but it did not significantly effect affect the levels of available P and exchangeable

K sediments. In fact, ridges + groundnut treatment containing of organic C and Ntot lowest in

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results for particular treatments. Losses of organic C and Ntot were significantly higher for the

control treatment than other treatments (Table 3).

Table 3. Nutrient content of sediments as a result of the application of soil conservation techniques on Areca areca land use

Treatment

≤ 0.05)

Sediment in the treatment of groundnut + ridges has lowest nutrient levels except for P,

while the highest levels were found for the control treatment and ridges + maize treatment. This

result is in contrast with the experiment on land use of cocoa, where maize selectively prevents

nutrient loss.

The loss of soil nutrient from control treatment was caused by the soil aggregates easily

broken down, and consequently the finer particles could be transported by runoff. This is the

major factor in land degradation, reducing the productivity and soil nutrients, such as soil

organic carbon (Fenton et al. 2005), phosphorus and nitrogen (Jokela & Casler 2011).

Oil Palm

Soil conservation on land use of oil palm also showing a significant effect on the levels of P

available, but it did not significantly affect on the levels of organic C, Ntot and exchangeable K

sediments. Soil conservation with cover crops Mucuna bracteata DC. contains P available

lowest in sediments (0.86 µg/g) (Table 4).

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Table 4. Nutrient content of sediments as a result of the application of soil conservation techniques on Oil Palm land use

Treatment

≤ 0.05)

In general, the yield of organic C and Ntot carried out by erosion is much greater than the

amount of P and K. This suggests that the loss of organic matter due to erosion is a more serious

problem because it accelerates land degradation and decline soil fertility. Amount of organic C

and Ntot in sediment indicates the magnitude of the potential loss of nutrients by erosion. This

is understandable due tobecause the properties of nitrogen are very susceptible to leaching,

being more mobile than phosphate. Therefore, soil conservation which also serves to maintain

soil organic matter content is a must, so that the level of organic matter in the soil is one indicator

of the sustainability of land resources (Wolf & Snyder 2003).

CONCLUSIONS

Results from this study show that ridges + ground nut most effectively reduces erosion on

the land use of cocoa, ridges + maize effectively reduce erosion on the areca land use, and

Mucuna bracteata DC. is more effective in the oil palm land use. Ridges + maize effectively to

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reduce the nutrient loss (organic-C, Ntot, av-P and exc-K) on the land use of cocoa, ridges +

ground nut also effectively reduce the nutrient loss (organic-C, Ntot, av-P and exc-K) on areca

land use, and Mucuna bracteata DC. effectively to decrease the loss of av-P in the oil palm land

use. The plant and ridges, in combination can improve the conservation effectiveness of soil

conservation approach, and they may be a practical and economical alternative to technical

conservation structures (such as terraces).

Acknowledgements. We would like to thank to the Ministry of Research, Technology and Higher Education Republic of Indonesia for the funding of this research through BPPS

scheme.

REFERENCES

BERTOL, I.B. ‒ MELLO, E.L. ‒ GUADAGNIN, J.C. ‒ ZAPAROLLI, A.L.V. ‒ CARRAFA, M.R. 2003. Nutrient losses by water erosion. In Scientia Agricola, vol. 60, p.581-586. BKPM, Komoditas Unggulan Daerah.

http://regionalinvestment.bkpm.go.id/newsipid/id/commodityarea.php?ia=11&ic=2580 diakses 15 desember 2012.

FENTON, T.E. ‒ KAZEMI, M. ‒ LAUTERBACH-BARRETT, M.A. 2005. Erosional impact on organic matter content and productivity of selected Iowa soils. In Soil and Tillage Research, vol. 81, pp. 163-171.

FITRI, R. 2010. Planning of farming system based on Areca catechu L for sustainable agricultural development in South Peusangan District of Aceh Province. In Proceedings of

the National Seminar and Annual Meeting of the Dean of Agricultural Sciences BKS – PTN West Regional 2010. Faculty of Agriculture, University of Bengkulu. ISBN 979-602-96609-8-2, pp. 548.

FUADY, Z. ‒ SATRIAWAN, H. 2011. Application of the mound to against the surface flow rate and erosion. In Proceedings of the National Seminar in Precision Farming. Post Graduate Forum, North Sumatera Utara University, Medan. Indonesia. ISBN 979-458-591-2, pp. ?

Commented [SVS2]: AQ: Please spell out BPPS.

Commented [U3]: Its possible more specify this reference (see instruction for authors)?

Commented [U4]: Please check if is right ISBN

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GOMEZ, J.A. ‒ SOBRINO, T.A. ‒ GIRALDEZ, J.V. ‒ FERERES, E. 2009. Soil management effects on runoff, erosion and soil properties in a olive grove of Southern Spain. In Soil & Tillage Research, vol. 102, no. 1, pp. 5-13.

HIDAYAT, Y. ‒ MURTILAKSONO, K. ‒ SINUKABAN, N. 2012. Characterization of surface runoff, soil erosion and nutrient loss on forest-agriculture landscape. In Journal of Tropical Soils, vol. 17, no. 3, pp. 259-266. DOI: 10.5400/jts.2012.17.3.259.

HUDSON, N.W. 1993. Field measurement of soil erosion and runoff. FAO soil bulletin 68. Food and Agricultural Organization of the United Nation, Rome. pp. 139.

JAE-YOUNG CHO ‒ KWANG-WAN HAN, 2002. Nutrient losses from a paddy field plot in Central Corea. In Water, Air, and Soil Pollution, vol. 134, pp. 215–228.

JOKELA, W. ‒ CASLER, M.D. 2011. Transport of phosphorus and nitrogen in surface runoff in a corn silage system: Paired watershed methodology and calibration period results. In Canadian Journal of Soil Science, vol. 91, pp. 479-491. DOI:10.4141/CJSS09095. NOER, H. 2011. Optimizing utilization of water resources through improved planting pattern

and repair cultivation techniques in farming systems. In Indonesian Journal of Agricultural Economics, vol. 2, no. 2, p.169-182.

NOERALAM, A.S. ‒ ARSYAD, S. ‒ ISWANDI, A. 2003. Control Techniques of Surface Flow on sloping dryland farming. In Jurnal Tanah dan Lingkungan, vol. 5, no. 1, pp. 13-16. PIMENTEL, D. 2006. Soil erosion: A food and environmental threat. In Environment,

Development and Sustainability, vol. 8, pp. 119-137. DOI 10.1007/s10668-1262-8. NARAIN, P. ‒SINGH, R.K. ‒ SINDHWAL, N.S. ‒ JOSHIE, P. 1998. Agroforestry for soil

and water conservation in the western Himalayan Valley region of India. In Agroforesty System, vol. 39, pp. 175–189.

SANCHEZ, M.M. ‒ SORIANO, M. ‒ DELGADO, G. ‒ DELGADO, R. 2002. Soil quality in mediterranian mountain environments: Effects of land use change. In Soil Science Society of

American Journal, vol. 66, pp. 948-958.

SATRIAWAN, H. ‒ DAN FUADY, Z. 2012. Referral Land Use For Agricultural Development in Peusangan Selatan Sub-district. In Proceedings of the National Seminar and Annual Meeting

of the Dean of Agricultural Sciences BKS – PTN West Regional 2012. Faculty of Agriculture University of Sumatera Utara. ISBN 979-458-597-1. pp. 497.

SATRIAWAN, H. ‒ HARAHAP, dan E.M. 2013. Study of soil erosion in Krueng Sieumpo Watershed Aceh. In Proceedings of the National Seminar on Community-Based Watershed Management Towards Sustainable Aceh Forest, Banda Aceh. ISBN 978-979-8278-89-1. pp. 171-180.

Formatted: Font: Italic

Formatted: Font color: Red

Commented [U6]: Please check if is right

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SATRIAWAN, H. ‒ HARAHAP, E.M. ‒ RAHMAWATY, ‒ KARIM, A. 2014. Land capability evaluation for agriculture in Krueng Sieumpo watershed, Aceh. In Academic Research International, vol. 5, no. 3, pp. 55-63.

SHARPLEY, A.N. ‒ SMITH, J. 1990. Soil erosion on agricultural land. In BOARDMAN, I.D.

‒ FOSTER, L. ‒ DEARING, J.A. (Eds.). Phosphorus Transport in Agricultural Runoff: The Role of Soil Erosion. John Wiley & Sons, pp. 351–366.

THOMAS, A.D. ‒WALSH, R.P.D. ‒SHAKESBY, R.A. 1999. Nutrient losses in eroded sediment after fire in eucalyptus and pine forests in the wet Mediterranean environment of northern Portugal. In Catena, vol. 36, pp. 283–302.

WOLF, B. ‒ SNYDER, G.H. Sustainable Soils. The Place of Organic Matter in Sustainability Soils and Their Productivity. New York : Food Product Press. 2003. pp. 352.

ZUAZO, D.V.H. ‒ MARTÍNEZ, A.R. ‒ RUIZ, J.A. 2004. Nutrient losses by runoff and sediment from the taluses of orchard terraces. In Water, Air, And Soil Pollution, vol. 153, no. 1-4, pp. 355–373. DOI:10.1023/B:WATE.0000019956.17314.88.

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1

Halus Satriawan1_{, Erwin Masrul Harahap}2_{, Rahmawaty}2_{, Abubakar Karim}3 1_{Doctoral Student in Agricultural Science, North Sumatera University}

2_{North Sumatera University, North Sumatera, Indonesia} 3_{Syiah Kuala University, Aceh, Indonesia}

ABSTRACT

This study aimed to determine: (1) the rate of runoff and erosion on each type of land use, (2) the most effective soil conservation, (3) nutrient content in eroded soil. The study was conducted in land use Areca, Cocoa and Oil Palm,which were treated with a specific soil conservation techniques for the one year growing season. The results showed in for the Areca land use of Areca, that soil conservation with mound + maize produces the lowest erosion (1.68 t/ha). In For cocoa land use of cocoa, the ridges + groundnut treatment produced the lowest erosion (8.2 t/ha). OnForoil palm land use of oil palm, the cover crop of Mucuna bracteata

hads lowest erosion yield (12.2 t/ha). Soil conservation techniques has significantly affected theo levels of organic C and available P underon the cocoa land use of cocoa, where ridges + maize has lowest content of organic C and available P in soil sediment (1.03% and 0.69 ppm). Soil conservation on at Areca land use also has significantlyaeffect toon the levels of organic C and available N, but it did not affect significantly affect to the levels of available P and exchangeable K sediments., where ridges + groundnut containing of organic C and available N lowest in sediment (1.4% and 0.18%). Furthermore, soil conservation on land use of oil palm showed a significant effect on the levels of available P, but did not significantly affect on the levels of organic C, available N and exchangeable K sediments. Soil conservation with cover crops Mucuna bracteata contains available P lowest in sediments (0.86 ppm).

Keywords: soilerosion, nutrientlevels, sediment, soil conservation, land use.

1.Introduction

the productivity of all natural ecosystems as well as agricultural ecosystem (Pimentel et.al,

1995). Loss of soil through erosion also brings with itinvolves the nutrients contained in the

soil. Nutrients loss due to surface runoff and soil erosion carried away from agriculturale land

is the main cause of soil degradation of agriculture land (Bertol et.al, 2003). Nitrogen,

phosphorus, organic carbon, potassium, calcium, magnesium and sodium are the main nutrients

loss carried by overland flow and soil erosion (Hidayat et.al, 2012).

Krueng Sieumpo watershed is sub-watershed of Krueng Peusangan Watershed in Aceh

Commented [V1]: This study – repeats in next sentence.

Commented [V2]: Certainly not each, better mention those land uses which are really involved in your study.

Commented [V3]: This study – repetition. Try to find other formulation.

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Province, Indonesia,thatwhich was categorized as critical area under unappropriate land and

priority to be managementd.and In needs rehabilitation (Fitri, 2011). Viewed from land use,

tThe farmers in this area still do not useing their land has not in accordance with land capability

and suitability.;also none implementingNo conservation techniques are implemented and , both

in terms ofThe cropping patterns and farming practices are inappropriate (Satriawan et.al,

2014). Oil palm (Elaeis guineensis), Areca (Areca catechu L.) and Cocoa (Theobrema cacao

L.) are major crops in Kreueng Sieumpo watershed, which spread more dominant on land with

slopes between 9-45%. The land area for oil palm plantations in Krueng Sieumpo watershed

have increased rapidly, with 4644 ha of cultivation under 5 years since 2008 (BKPM, 2013).

But today, oil palm cultivation is limited to marginal areas such as hilly sloping lands where

they comprise about 60% of the marginal land areas (Satriawan and Fuady, 2012). Similarly to

with oil palm, cocoa is one of the main export commodity in Indonesia that many provide

foreign exchange, the more cultivated by farmers. The Aarea planted with under cocoa

plantation in Bireuen District in 2012 is 6023 ha and it still continues to growing until now with

an average productivity of 0.63 t/ha (BKPM 2013). Areca is also main crop of traditional

plantation with 7782 ha of cultivation area and productivity of 1.5 t/ha of dry beans. As a result

of land use patterns, the predicted rate of soil erosion on cultivated land reaches from 54.6 to

1007.6 t/ha/year (Satriawan and Harahap, 2013), is still higher than the tolerable erosion in this

region ranging from 25.1 to 40 t/ha/year (Fitri, 2010).

The aims of soil conservation for growing more production can be achieved by using land in

accordance with its capabilities, to apply measures to restore the productivity of the soil where

it has been damaged and to prevent further damage from taking place, and to combine sound

methods of soil management with other methods and inputs of modern agriculture to obtain

satisfactory production on sustainabled basis (Hudson, 1993).

Commented [V5]: bad grammar

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Numerous studies have evaluated the pollution by nutrients currently used in agriculture

(Sharpley and Smith, 1990; Pratap Narain et.al, 1998; Thomas et.al, 1999; Jae-Young Cho and

Kwang-Wan Han, 2002; Zuazo et.al, 2011). The erosion plot method for direct evaluation in

the field is the most effective to quantify water erosion (Sanchez et.al, 2002). Therefore, it

became necessary to quantify soil erosion more extensively, with the aim of providing a tool

for planning soil conservation strategies for many land use types on watershed basis. The

objectives of this study were to determine: (1) the rate of runoff and erosion on each types of

land use, (2) nutrient contents in eroded soil, (3) the most effective soil conservation.

2.Material and Method

Study Area

were located at Krueng Sieumpo watershed (5o_{4′37.65′′ N and 96}o_{45′44.91′′ E}_{). Th}_{ree crops}

were tested:e form of land use Areca, Cocoa and Oil Palm were treated withunder a specific

soil conservation techniques. The experiment lasted for the one year application (June

2013-July 2014). The area was cultivated with 2 years old oil palm trees, 5 years old areca trees and

3 years old Cocoa. Average annual rainfall in this area was 1818 mm, and the daily mean air

temperature was 27.6o_{C. The soil of the experimental area is classified as Typic Paleudult,}

which has sandy clay in the topsoil (0-15 cm depth).

Experimental Design

The field experiment layout was has a completely randomized block design with three

replications. The conservation practices in land use of areca was tested fFour treatments were

tested for each land use (three conservation practices and the conventional treatment as

control):. The conservation practices were not the same for each land use type. For areca trees

it was 1) control (none soil conservation); 2) ridges + green beans; 3) ridges + groundnut; 4)

ridges + maize., In land use ofor cocoa was tested four treatments: 1) control (none soil

Commented [V7]: pollution of what? Water courses, water reservoirs, water sources, sea? Which nutrients ? N or P or both?

Commented [V8]: Put here the reference of USDA taxonomy

(19)

conservation); 2) ridges + green beans; 3) ridges + groundnut; 4) ridges + maize. andOn land

use ofor oil palm was tested four treatments: 1) control (none soil conservation); 2) green beans;

3) Mucuna bracteata; 4) sediment trap + maize.

The erosion plots were located on the hilly slopes at of 25% (15o_{) inclin}_atione_{, with}_an

acreage of 20 m2_{(4 x 5 m)}_oi_{n Cocoa and Areca area, and 80 m}2_{(4 x 20 m)}_oi_{n oil palm area.}

Each erosion plot consisted of a galvanized enclosure, drawer collector, sediment and runoff

collector (ϴ 0.6 m, 0.8 m high). The application rate of chemical fertilizer during the study was

as follows: the total amount of fertilizers (150 kg N/ha, 100 kg P/ha, and 75 kg K/ha) was

applied for each treatment.

Measurement of runoff and erosion was conducted infor each rainfall events during the

period of the experiment. Erosion measurements performed involved theby measurementing of

the runoff volume of runoff in plot erosion. and the measurement of Eeroded soil. The weight

of soil sediment was measured by filtering the water samples using filter paper.,tThe soil left

on the filter paper was dried in an oven at 60 °C until the sediment weight of sedimentsbecame

constant. The amount of sediment (E) is calculated using the following equation:

A

(extraction with 1 N NH4OAc pH 7.0). The yield of organic C, available N, available P and

exchangeable K carried by runofferosion was calculated by the equation:

Commented [V10]: Photographs of the plots with crop growths is needed

(20)

X = Y x E

Explanation:

X = Yield of organic C, available N, available P and exchangeable K carried erosion (kg/ha) Y = concentration of organic C (%), total Nitrogen (%), available P (µg/g) and exchangeable K (cmol/kg) in sediment

E = total amount of eroded soil (t/ha)

were subjected to ANOVA procedure, and means separation test was done by protected Least

Significant Difference (LSD) test at 5% level of significance.

3.Result and Discussion Runoff and Soil Erosion

Soil conservation techniques tested on the 3 investigated land use types of land use showed

not significantlyhad smallaeffect on the runoffflow of surface, but it’s they hadve significant

effects to controlling soil erosion rate (table 1).

Land use

Treatment Cocoa Runoff Areca Treatments Oil Palm (m3_/ha) Erosion _(t/ha) Runoff _(m3_/ha) Erosio_{n (t/ha)} Runoff _(m3_/ha) Erosion _(t/ha)

Table 1 presentstotal all runoff events monitored during the experiment. The runoff fluxes

of from testedthe treatments on Cocoa land use ranged from 210.8 to 243.22 m3_/ha_{for Cocoa}

land use, 207.04 to 243 m3_/ha_{on for}_{Areca land use, 199.5 to 238.95 m}3_/ha_{on for}_{Oil palm}

treatment, respectively. On For cocoa land use of cocoa,the soil conservation with groundnut

Commented [V12]: Unify the decimal point for all values

(21)

+ ridges consistently produceds the lowest erosion as compared to three other methods (8.2

t/ha), and as compared with to the control treatment, the erosion under groundnut + ridges

decreased by 79.61%. Then, on the areca land use,the implementation of soil conservation

maize + ridges treatment shows high ability for controlling the erosion (4.68 t/ha), slightly better

than green beans + ridges treatment, but it is much more effective than groundnut + ridges and

control,(decreasedby 76.47%). While on at oil palm land use, the soil conservation with land

coverMucuna bracteatatreatment was most effectively to controlling the erosion (12.20 t/ha),

followed by maize + ridges treatment (12.33 t/ha). Two other treatmentsconservation technique

(green beans and control) resulteds in greater erosion. As cCompared with to the control

treatment, the erosion under Mucuna bracteata decreased by 34.61%.

The results showed that the application of intercropping system accompanied bycomined

with a ridges is quite effective to reduce erosion and runoff on at land use Cocoa and Areca

land uses. Ridges modifieds thesoil surface soil to becomes more rugged and served as a water

collector. Similarly, a denser plant populations cover and stratified canopy on intercropping

systems can reduced the rain erosivity through interception, and increase of infiltration due to

the diversity of plant root systems. Instead contraary the runoff and erosion on at control

treatmentwasare lower as compared to the treatment of maize + ridges and green beans + ridges

treatmentproduces the highest erosion. In At the control treatment, runoff during rain have no

barrier, so that the movement of runoff could bring transport soil particles. The results of this

study are consistent with the study of Noeralam et.al (2003) who reported that the application

of ridges with canal effectively suppress reduced the overland flow /runoff by 50.8 %.

(Noeralam et.al, 2003) Similarly,and 63.5% ( Fuady and Satriawan, (2011), report 63.5%

reduction and erosion until to 67.5% compared without the application of conservation

techniques, (both in the period of vegetative and generative). Moreover, the results indicated

(22)

2009; Shen et.al, 2010) In the application of soil conservation in oil palm land use, treatment

of Mucuna bracteata, maize + sediment trap among oil palm trees show significantly different

erosion between control and green beans treatment.

The use of cover crops such as Mucuna bracteata can reduce the rate of runoff and erosion

through the reduction of the increased volume of water absorption / infiltration, and

improvement of soil physical properties and also maythe reductione ofnegative effects of high

rainfall impact. High rainfall can cause soil granules broken and crushedintensive detachment

of soil particles, so the soil becames easily eroded, but with alley cropping, fertilization and the

use of mulching can reduce soil erosion until to tolerable levelimits (Noer, 2011). Probable

mechanisms for the greater sediment reductione in this study are linked with changes in flow

dynamics through at least three processes. First, the vegetative barrier and ridges may intercept

concentrated flow by decreasing velocity and dispersing runoff; Second, increased ponding

may promote deposition of sediment; Third, the ponding may absorb runoff energy that would

cause soil detachment and transport and, thus reduceing the erosion and transport capacity.

Nutrient Loss

Soil conservation also affects the nutrient loss in together with the sediment. Tables 2, 3 and

4 show for each land use there are different effects of soil conservation in each land use on

levels of organic C, total N, available P and exchangeable K. Soil conservation techniques can

reduce the amount of erosion rates as well asand also decreases the amount of organic C and

nutrients carried by erosionrunoff.

Cocoa

Soil conservation techniques have significantly affected to levels of organic C and available

P on for the cocoa land use of cocoa,howeverbut the levels of total N and exchangeable K did

not differ on sediment erosion. Soil conservation with Rridges + maize treatment showedhas

lowest content of organic C and available P in soil sediment (1.03% and 0.69 µg/g) (table 2).

(23)

But in contrast to the total weight of nutrients (kg/ha), all parameters showed a difference to the

control treatment.

Table 2. Nutrient content of sediments as a result of the application of soil conservation techniques on Cocoa land use

Perlakuan

Parameter

Organic C Ntot Pav Kexc

(%) kg/ha (%) kg/ha µg/g kg/ha cmol/kg kg/ha ridges +

ground

nut 1.46

b_119.33a _0.17a _13.17a _2.94b_0.03a _0.95 _0.07a

ridges +

maize 1.03a 283.75a 0.12a 31.90b 0.69a 0.02a 0.80 0.22b ridges +

green

beans 2.11

b_{376.87ab 0.19}a _34.62b _3.73c_{0.07ab 0.83} _0.15ab

Control 1.76b_{710.49b 0.16}a _64.30c _2.28b_0.15b _0.92 _0.37c

Means in the same column, followed by different lettersmarked by indices, are significantly different, based on the LSD (p ≤ 0.05)

Level of Tthe nutrient content in sediment produced is shows linear correlation with the number

amount of eroded soil eroded. In this study the lowest erosion was found recorded in for

treatment groundnut + mounds treatment. These results indicate that the characterisztics of the

plant such as the type of plants, roots, and the period of growth has contributed effect onto

suppress leaching through erosion. the results of this study,mMaize is most effective to prevent

loss of nutrients through intensively nutrient absorption mechanism by roots, thus means

selectivity of erosion by the maize is better than the other plants. In addition, mounds serves

helps to inhibit surface flow and supports the deposition of particles carried by runoff,

depositing soil particles are dispersed so as not to pass through the outlets.

Areca

Soil conservation on Areca land use also has also significantlyaeffect onto the levels of

organic C and N tot, but it did not significantly aeffect to the levels of available P and

exchangeable K sediments, where ridges + groundnut containing of organic C and N tot lowest

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results among for particular treatments. Losses of organic C and Ntot were significantly higher

in for the control treatment than for other treatments (Table 3).

Table 3. Nutrient content of sediments as a result of the application of soil conservation techniques on Areca land use

Perlakuan

Parameter

(%) kg/ha (%) kg/ha µg/g kg/ha cmol/kg kg/ha ridges +

ground nut 1.40a 185.98a 0.18a 23.87b 2.35 0.031a 0.84 0.112ab ridges +

maize 1.80a 83.49a 0.34b 15.93a 2.10 0.010a 1.00 0.046a ridges +

green beans 1.83a 127.32a 0.23a 15.67a 3.68 0.026a 0.91 0.063ab Control 3.86b _{757.73b 0.41}b _{80.65c 1.24} _0.025a _0.95 _0.188b

Means in the same column, followed by different letters, are significantly different, based on the LSD (p ≤ 0.05)

Sediment in the treatment of groundnut + ridges has lowest nutrient levels except forthe

parameter P in the sediment, while the highest levels wereas found infor the control treatment

and maize + ridges treatment. This result is contrast with the experiment on land use of Cocoa,

where maize is selectively prevents nutrient loss.

Oil Palm

Soil conservation on oil palm land use of oil palm also showsing a significant effect on the

levels of P available, but it did not significantly aeffect on the levels of organic C, N tot and

exchangeable K in the sediments. Soil conservation with cover crops Mucuna bracteatashowed

the lowest contains P available P lowest content in sediments (0.86 µg/g) (Table 4).

Table 4. Nutrient content of sediments as a result of the application of soil conservation techniques on Oil Palm land use

Perlakuan

Parameter

(%) kg/ha (%) kg/ha µg/g kg/ha cmol/kg kg/ha Green beans 1.55 285.48a 0.19 35.77a 3.86b_{0.07b 0.35} _0.18b Mucuna

bracteata 1.80 220.34a 0.24 29.72a 0.86a 0.01a 0.50 0.11a

Maize+Sediment

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Control 2.62 470.20a 0.17 30.39a 2.40a_{0.04ab 0.34} _0.16b

Means in the same column, followed by different letters, are significantly different, based on the LSD (p ≤ 0.05)

In general, the yield of organic C and Ntot carried out by erosion is much greater than the

amount of P and K. This suggests that the loss of organic matter due to erosion is a more serious

problem because it accelerates land degradation and declineing of soil fertility. Amount of Ntot

in sediment indicates soil losses on soil with loss of Nitrogen carried by erosion. This is

understandable due to the properties ofas nitrogen are is very susceptible to leaching being,that

are relativelymore mobile compared withthanPphosphate. Therefore, soil conservation which

also serves to maintain soil organic matter content is a must, so that the level of organic matter

in the soil is one indicator of the sustainability of land resources (Wolf and Snyder, 2003).

4.Conclusion

Results from this study show that ridges + ground nut most effectively reduce erosion on

land use of cocoa, ridges + maize effectively reduce erosion on areca land use, and Mucuna

bracteata is more effective in the oil palm land use. Ridges + maize effectively to reduce the

nutrient loss (organic-C, Ntot, av-P and exc-K) on land use of cocoa, ridges + ground nut also

effectivelyto reduce on the nutrient loss (organic-C, Ntot, av-P and exc-K) on areca land use,

and Mucuna bracteatais effectivelyto decrease the loss of av-P in the oil palm land use. Our

suggestiontothat useoftheconservation cropplant and ridges, when used in combination can

improve theo conservation effectiveness of soil conservation approach, and they may be a

practical and economical alternative to technical conservation structures (such as terraces)for

reducing soil and nutrient loss.

Commented [V17]: Sentence is not understandable.

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Acknowledgements

I would like to thank to the Ministry of Education and Cultureal of Republic of Indonesia for

the funding of this research through BPPS scheme. I also would like to thank to Surya, Darma,

Fauzan, Azhar, Masriadi, and Fajri for their contribution and help especially during the

fieldwork.

References

Bertol I, EL Mello, JC Guadagnin, ALV Zaparolli, and MR Carrafa. Nutrient Losses by Water Erosion. Sci Agric 2003. 60: 581-586.

Fitri. R. 2010. Planning of Farming System Based on Areca catechu L for Sustainable Agricultural Development in South Peusangan District of Aceh Province. Proceedings of the National Seminar and Annual Meeting of the Dean of Agricultural Sciences BKS – PTN West Regional 2010. Faculty of Agriculture, University of Bengkulu. ISBN 979-602-96609-8-2. p 548

Fuady, Z., Satriawan, H. 2011. Application of the mound to against the Surface Flow Rate and Erosion. Proceedings of the National Seminar in Precision Farming. Post Graduate Forum, North Sumatera Utara University, Medan. Indonesia. ISBN 979-458-591-2. Gomez JA, Sobrino TA, Giraldez JV, Fereres E, 2009. Soil management effects on runoff,

erosion and soil properties in a olive grove of Southern Spain. Soil & Tillage Research 102 (1):5-13.

Hidayat. Y., K. Murtilaksono and N. Sinukaban. Characterization of Surface Runoff, Soil Erosion and Nutrient Loss on Forest-Agriculture Landscape. J Trop Soils, Vol. 17, No. 3, 2012: 259-266 ISSN 0852-257X. DOI: 10.5400/jts.2012.17.3.259

Hudson. N.W. Field measurement of soil erosion and runoff, FAO soil bulletin 68. Food and Agricultural Organization of the United Nation, Rome. 1993.

Jae-Young Cho and Kwang-Wan Han: 2002, ‘Nutrient losses from a paddy field plot in Central Corea’, Water, Air, and Soil Pollut. 134, 215–228.

Noer., H. 2011. Optimizing Utilization of Water Resources Through Improved Planting Pattern And Repair Cultivation Techniques In Farming Systems. Indonesian Journal of Agricultural Economics Vol. 2 No. 2. p.169-182. 2011. ISSN 2087 - 409X

Noeralam, A.S., S. Arsyad, and A. Iswandi, 2003. Teknik Pengendalian Aliran Permukaan yang efektif pada usahatani lahan kering berlereng. Jurnal Tanah dan Lingkungan. Vol 5 (1) : 13-16

Pratap Narain, Singh, R. K., Sindhwal, N. S. and Joshie, P.: 1998, ‘Agroforestry for soil and water conservation in the western Himalayan Valley Region of India’, Agrofor. Syst.

39, 175–189.

Satriawan. H., dan E.M. Harahap. 2013. Study of soil erosion in Krueng Sieumpo Watershed Aceh. Proceedings of the National Seminar on Community-Based Watershed

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Management Towards Sustainable Aceh Forest, Banda Aceh. ISBN: 978-979-8278-89-1. P. 171-180

Shen Z, Y. Gong, Y. Li, R. Riu, 2010. Analysis and modelling of soil conservation ,easures in the Three Gorges Reservoir Area in China. Catena 81:104-112.

Sharpley, A. N. and Smith, J.: 1990, ‘Soil Erosion on Agricultural Land’, in I. D. Boardman, L. Foster and J. A. Dearing (eds), Phosphorus Transport in Agricultural Runoff: The Role of Soil Erosion, John Wiley & Sons, pp. 351–366.

Thomas, A. D.,Walsh, R. P. D. and Shakesby, R. A.: 1999, ‘Nutrient losses in eroded sediment after fire in eucalyptus and pine forests in the wet Mediterranean environment of northern Portugal’, Catena 36, 283–302.

Wolf B, Snyder GH. Sustainable Soils. The Place of Organic Matter in Sustainability Soils and Their Productivity. London: Food Product Press. 2003.

Zuazo, D.V.H., A.R. Martínez and. J.A. Ruiz., 2004. Nutrient Losses By Runoff And Sediment From The Taluses Of Orchard Terraces. Water, Air, And Soil Pollution 153: 355–373,

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1

Halus Satriawan1_{, Erwin Masrul Harahap}2_{, Rahmawaty}3_{, Abubakar Karim}4 1_{Doctoral Student in Agricultural Science, North Sumatera University,}

2,3_{North Sumatera University, North Sumatera, Indonesia} 4_{Syiah Kuala University, Aceh, Indonesia}

ABSTRACT

This study aimed to determine: (1) the rate of runoff and erosion on types of land use, (2) the most effective soil conservation, (3) nutrient content in eroded soil. It’s was conducted in land use Areca, Cocoa and Oil Palm were treated with a specific soil conservation techniques for the one year growing season. The results showed in the land use of Areca, soil conservation with mound + maize produces the lowest erosion (1.68 t/ha). In land use of cocoa, ridges + groundnut treatment produce the lowest erosion (8.2 t/ha). On land use of oil palm, cover crop of Mucuna bracteata has lowest erosion yield (12.2 t/ha). Soil conservation techniques affect

to levels of organic C and available P on the land use of cocoa, where ridges + maize has lowest content of organic C and available P in soil sediment (1.03% and 0.69 ppm). Soil conservation on Areca land use also has significantly affect on the levels of organic C and available N, but did not significantly affect to the levels of available P and exchangeable K sediments, where ridges + groundnut containing of organic C and available N lowest in sediment (1.4% and 0.18%). Furthermore, soil conservation on land use of oil palm showed a significant effect on the levels of available P, but did not significantly affect on levels of organic C, available N and exchangeable K sediments. Soil conservation with cover crops

Mucuna bracteata contains available P lowest in sediments (0.86 ppm).

Keywords: soilerosion, nutrientlevels, sediment, soil conservation, land use.

1.Introduction

the productivity of all natural ecosystems as well as agricultural ecosystem (Pimentel et.al, 1995) . Loss of soil through erosion also brings with it nutrients contained in the soil.

Nutrients loss due to surface runoff and soil erosion carried away from agriculture land is the

main cause of soil degradation of agriculture land (Bertol et.al, 2003). Nitrogen, phosphorus,

organic carbon, potassium, calcium, magnesium and sodium are the main nutrients loss

carried by overland flow and soil erosion (Hidayat et.al, 2012).

Krueng Sieumpo watershed is sub-watershed of Krueng Peusangan Watershed in Aceh Province, Indonesia that was categorized as critical and very priority for rehabilitation (Fitri,

Commented [a1]: and

Commented [a2]: Indonesia

Commented [a3]: not on the references

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2011). Based on land capacity, the farmers in this area utilizing land resources are not based on land capability and land suitability; and do not apply soil conservation techniques, both in

terms of cropping patterns and farming practices (Satriawan et.al, 2014). Oil palm (Elaeis guineensis), Areca (Areca catechu L.) and Cocoa (Theobrema cacao L.) are major crops in

Kreueng Sieumpo watershed, which spread more dominant on land with slopes between

9-45%. The land area for oil palm plantations in Krueng Sieumpo watershed have increased

rapidly, with 4644 ha of cultivation under 5 years since 2008 (BKPM, 2013). But today, oil palm cultivation is limited to marginal areas such as hilly sloping lands where they comprise

about 60% of the marginal land areas (Satriawan and Fuady, 2012). Similar with oil palm, Cocoa is one of the major export commodities in Indonesia that many give country income,

the more cultivated by farmers. Area planted with cocoa in Bireuen District in 2012 is 6023

ha and continues to grow until now with an average productivity of 0.63 t/ha (BKPM 2013). Areca is also main crop of traditional plantation with 7782 ha of cultivation area and

productivity of 1.5 t/ha of dry beans. As a result of land use patterns, the predicted rate of soil

erosion on cultivated land reaches from 54.6 to 1007.6 t/ha/year (Satriawan and Harahap,

2013), still higher than the tolerable erosion in this region from 25.1 to 40 t/ha/year (Fitri,

2010).

The aims of soil conservation for growing more production can be achieved by using land

in accordance with its capabilities, to apply measures to restore the productivity of the soil

where it has been damaged and to prevent further damage from taking place, and to combine

sound methods of soil management with other methods and inputs of modern agriculture to

obtain satisfactory production on sustained basis (Hudson, 1993 ).

Numerous studies have evaluated the pollution (water courses) by nutrients currently used

in agriculture (Sharpley and Smith, 1990; Pratap Narain et.al, 1998; Thomas et.al, 1999;

Jae-Young Cho and Kwang-Wan Han, 2002; Zuazo et.al, 2011). The erosion plot method for

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direct evaluation in the field is the most effective to quantify water erosion (Sanchez et.al,

2002). Therefore, it became necessary to quantify soil erosion more extensively, with the aim

of providing a tool for planning soil conservation strategies for many land use on watershed

basis. The objectives of this study were to determine: (1) the rate of runoff and erosion on

each types of land use, (2) nutrient contents in eroded soil, (3) the most effective soil

conservation.

2.Material and Method Study Area

were located at Krueng Sieumpo watershed (5o_{4′37.65′′ N and 96}o_{45′44.91′′ E}_{). The form of}

land use Areca, Cocoa and Oil Palm were treated with a specific soil conservation technique

for the one year application (June 2013-July 2014). The area was cultivated with 2 years old

oil palm trees, 5 years old areca trees and 3 years old Cocoa. Average annual rainfall in this

area was 1818 mm, and the daily mean air temperature was 27.6o_{C. The soil of the}

experimental area is classified as Typic Paleudults, which has sandy clay in the topsoil (0-15

cm depth).

Experimental Design

The field experiment layout was a completely randomized block design with three replicas.

Soil conservation techniques were tested on land use areca are four treatments: 1) control (no

soil conservation); 2) ridges + green beans; 3) ridges + groundnut; 4) ridges + maize.

Furthermore, on land use of cocoa was tested four treatments: 1) control (no soil

conservation); 2) ridges + green beans; 3) ridges + groundnut; 4) ridges + maize. On land use

of oil palm was tested four treatments: 1) control (no soil conservation); 2) green beans; 3)

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The erosion plots were located on the hilly slopes at 25% (15o_{) incline, with 20 m}2_{(4 x 5}

m) on Cocoa and Areca area (figure 2 and 3), and 80 m2_{(4 x 20 m) on oil palm area (}_figure

4). Each erosion plot consisted of a galvanized enclosure, drawer collector, sediment and

runoff collector (ϴ 0.6 m, 0.8 m high). The application rate of chemical fertilizer during the

study was as follows: the total amount of fertilizers (150 kg N/ha, 100 kg P/ha, and 75 kg

K/ha) was applied for each treatment.

Figure 1. sketch the ridges and sediment collector at the experimental plots

Ridges are constructed of two pieces with 20 cm high and 25 cm width (figure 1 ).

Measurement of runoff and erosion was conducted in each rainfall events during experiment.

Erosion measurements performed by measuring the volume of runoff in plot erosion. Eroded

soil (suspended sediment sampling of water flow) weight was measured by filtering the water

samples using filter paper, the soil left on the filter paper was dried in an oven at 60 ° C until

weight of sediments constant. The amount of sediment (E) is calculated using the following

equation:

2.5 m 20 cm

Tillage field

channel

ridges Land slope

25 cm

Sediment collector

Pipe  8 cm.

20 cm

Commented [a10]: Figure

(32)

A x V x C

E ap ap

3 10 

Explanation:

E : eroded soil (t/ha)

Cap : Concentration of sediment load (kg/m3) Vap : Volume of runoff (m3₎

A : wide area (ha)

10-3 _{: unit conversion kg to ton}

Figure 2. experiment plot on Cocoa

Figure 3. experiment plot on Areca

Sediment analysis conducted to measure the content of organic C (Ctot) (Walkley-Black

(33)

(extraction with 1 N NH4OAc pH 7.0). The nutrient loss (organic C, available N, available P

and exchangeable K) were calculated by the equation:

X = Y x E

Explanation:

X = Total nutrient loss (organic C, available N, available P and exchangeable K) (kg/ha) Y = concentration of organic C (%), total Nitrogen (%), available P (µg/g) and exchangeable K (cmol/kg) in sediment

E = total of eroded soil (t/ha)

were subjected to ANOVA procedure, and means separation test was done by protected Least

Significant Difference (LSD) test at 5% level of significance.

Figure 4. experiment plot on oil palm

3.Result and Discussion Runoff and Soil Erosion

Soil conservation techniques on the 3 types of land use showed not significantly affect the

flow of surface, but it’s have significant effects to controlling soil erosion (table 1 ).

Land use

Treatment Cocoa Runoff Areca Treatments Oil Palm (m3_/ha) Erosion _(t/ha) Runoff _(m3_/ha) Erosion _(t/ha) Runoff _(m3_/ha) Erosion _(t/ha)

ridges +

green 243.22 17.86b 243 6.99b Green beans 200.18 18.66b

(34)

beans ridges +

maize 231.79 27.39c 224 4.64a Mucuna bracteata 199.5 12.20a

ridges +

groundnut 210.18 8.2a 207.04 13.23c Maize+ sediment trap 221.11 12.33a Control 227.52 40.22d _{215.20 19.72}d _Control _238,95 _17.97b

LSD

p≤0.05 2.75 1.43 LSD p≤0.05 1.85

In the same column, value with different letter are significantly different from one another at the LSD (p ≤ 0.05) test.

Table 1 present total runoff events monitored during experiment. The runoff fluxes of the

treatments on Cocoa land use ranged from 210.8 to 243.22 m3_{/ha, 207.04 to 243 m}3_{/ha on}

Areca land use, 199.5 to 238.95 m3_{/ha on Oil palm, respectively. On land use of cocoa, soil}

conservation with groundnut + ridges consistently produces the lowest erosion compared to three other methods (8.2 t/ha), compared with the control treatment, the erosion under

groundnut + ridges decreased by 79.61%. Then, on the areca land use, implementation of soil conservation maize + ridges show high ability for controlling the erosion (4.68 t/ha), slightly better than green beans + ridges treatment, but it is more effective than groundnut + ridges and control, decreased 76.47%. While on oil palm land use, soil conservation with land cover

Mucuna bracteata most effective to controlling erosion (12.20 t/ha), followed by maize +

ridges (12.33 t/ha). Two other conservation technique (green beans and control) results

greater erosion. Compared with the control treatment, the erosion under Mucuna bracteata

decreased 34.61%.

The results showed the application of intercropping system accompanied by a ridges quite

effective to reduce erosion and runoff on land use Cocoa and Areca. Ridges modifies surface

soil becomes more rugged and serve as a water collector. Similarly, a denser plant populations

and stratified canopy on intercropping systems can reduce the rain erosivity through

interception, and increase infiltration due to the diversity of plant root systems. Instead runoff

on control are lower compared to the treatment of maize + ridges and green beans + ridges

produces the highest erosion. In the control treatment, runoff during rain have no barrier, so

(35)

that the movement of runoff could bring soil particles. The results of this study are consistent

with report that application of ridges with canal effectively suppress overland flow /runoff

50.8 % (Noeralam et.al, 2003) and 63.5% (Fuady and Satriawan, 2011), and erosion until

67.5% compared without the application of conservation techniques, both in the period of

vegetative and generative. Moreover, the results indicated that the beneficial in controlling

soil erosion, similar to other previous studies (Gomez et.al, 2009; Shen et.al, 2010) In the

application of soil conservation in oil palm land use, treatment of Mucuna bracteata, maize +

sediment trap among oil palm trees show significantly different erosion between control and

green beans treatment.

The use of cover crops such as Mucuna bracteata can reduce the rate of runoff and erosion

through the reduction of the increased volume of water absorption / infiltration and

improvement of soil physical properties and also may reduce negative effects of high rainfall.

High rainfall can cause soil granules broken and crushed, so easily eroded, but with alley

cropping, fertilization and the use of mulch can reduce soil erosion until tolerable limits

(Noer, 2011). Probable mechanisms for the greater sediment reduce in this study are linked

with changes in flow dynamics through at least three processes. First, the vegetative barrier

and ridges may intercept concentrated flow by decreasing velocity and dispersing runoff;

Second, increased ponding may promote deposition of sediment; Third, ponding may absorb

runoff energy that would cause soil detachment and transport, reducing the erosion and

transport capacity.

Nutrient Loss

Soil conservation also affects the nutrient loss in the sediment. Tables 2, 3 and 4 show there

are different effects of soil conservation in each land use on levels of organic C, total N,

available P and exchangeable K. Soil conservation techniques can reduce the amount of