Conservation of soil moisture through tillage, residue mana

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Studies on moisture conservation in rice and lentil systems

Study 1: Conservation of soil moisture through tillage, residue management and plant type in rice-lentil system (Upland terrace condition, moisture stress from early vegetative stage to maturity).

a) Upland situation Tillage:

T1: Conventional tillage (CT- 3 Ploughing, levelling) - Zero tillage (ZT-opening narrow furrow in between standing rice stubbles)

T2: Minimum tillage (MT-1 ploughing, levelling) - ZT T3: ZT - ZT

Rice residue management:

R1 - Residue removal, R2 - Standing residue 20cm, R3 - Standing residue 40cm, R4 - Mulching

Lentil varieties:

L1 - Early with high biomass (DPL 62)

L2 - Medium duration with high biomass (DPL 15) Control for lentil

 Conventional tillage & residue management (CT-CT)

 Conventional tillage & mulching (CT-CT+R)

Study 2: Manipulation of soil moisture through plant type, residue management and balanced nutrition for successful lentil production in lowland land rice fallow (Low land, occasional moisture stress at vegetative stage/flowering stage)

b. Lowland situation Treatments

Rice varieties:

V1- Long duration (local, Mendri) V2- Early (HYV, Shahsarang 1) Rice residue management:

R1- Standing stubble (20cm), R2- Standing stubble (40cm) R3- Residue removal

Lentil varieties: Early with high biomass (DPL 81) vs. Medium duration with high biomass (IPL 406)

N.B. Lentil was sown under zero tillage with manual furrow opener with medium dwarf varieties.

Drainage channel (30x30 cm) around rice plot at physiological maturity.

Sowing of lentil crop in lowland situation could not be carried out immediately after harvesting of paddy due to excess soil moisture in spite of the fact that drainage around the field was done at the physiological maturity of rice.

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It was noted that Local rice variety Mendri taken longer duration to mature in comparison to the improved medium duration variety Shahsarang 1.

Taking the advantages of comparatively shorter duration of Shahsarang 1, sowing of lentil could be made earlier, but due to the excess soil moisture as noted above sowing dates could not be exploited fully.

7. Progress made during the year:

Weather data during the crop period:

In general, the year 2011 received a good rainfall (2617.1 mm) exceeding the average annual rainfall by 7%. The rainfall extended up to the month of November-December, which was good for upland crops but caused delay in planting of lentil in lowland land due to excess moisture in rice fallow. Graphical representations of monthly weather data of the year 2011-2012 are given below:

Weather parameters during experimental period (June 2011- April 2012)

Fig 1: Weekly average rainfall, relative humidity, minimum temperature, maximum temperature, and sunshine hours during crop growing season

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Progress made during the year:

Initial soil physico-chemical and microbial properties before sowing of lentil

The soil of the experimental site is sandy clay in lowland and sandy clay loam in upland field. The initial soil parameters are presented in Table 1.

Table 1: The physico-chemical properties and microbial activity

a) Chemical properties of soil before sowing of lentil Field

situation

Organic carbon (%)

Available N (kg/ha) Available P (kg/ha) Available S (kg/ha) Upland 0-5 cm 1.57

258.10 9.43 26.8 5-10 cm 1.50

10-15 cm 1.45 Lowland 0-5 cm 2.14

261.80 10.97 22.3 5-10 cm 2.05

10-15 cm 1.95

b) Physical properties of soil before sowing of lentil Field

situation

Bulk density (g/cm3) Water Holding Capacity

(%)

Plant Available

water (FC-PWP)

(%)

Mean weight diameter

(MWD) (mm)

Infiltration rate (mm/hr)

Sat. Hydraulic conductivity

(mm/hr)

Soil texture Sand Silt Clay

Upland 0-5 cm 1.16

48.9 16.5 2.18 4.02 28

61.5 13.2 25.3 5-10 cm 1.24

10-15cm 1.30 Lowland 0-5 cm 1.07

56.46 17.2 4.14 3.14 10

49.8 11.4 38.7 5-10 cm 1.18

10-15cm 1.28 c) Microbial parameters

Field situation Soil Microbial Biomass Carbon (SMBC) (µg/g dry soil)

Dehydrogenase enzyme activity (µg/g TPF)

Upland 75.2 2.12

Lowland 156.1 2 2.17

Study 1

Conservation of soil moisture through tillage, residue management and plant type in rice- lentil system (Upland terrace condition, moisture stress from early vegetative stage to maturity).

Table 2. Performance of upland rice as influenced by tillage and residue management

Tillage Panicle/

m²

Grains/

panicle

Test wt.

(g)

Grain Yield (t/ha) Straw weight (t/ha)

Total Biomass (t/ha)

HI (%)

MT-ZT 310.30 93.2 29.3 4.39 7.91 12.30 35.69 CT-ZT 297.50 84.6 29.4 3.88 6.64 10.52 36.89 ZT-ZT 322.25 98.8 29.8 4.71 7.71 12.42 37.92 CT-CT

(Retention) 278.50 84.4 29.6 4.17 6.60 10.78 38.69 CT-CT (Removal) 285.60 79.5 28.7 3.78 6.88 10.65 35.47

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Fig 3. Crops under different treatments after rice harvest (upland)

Lentil under zero tillage (Residue removal) Lentil under zero tillage (mulching) Lentil under zero tillage Lentil sowing under zero tillage using a

furrow opener

Fig 2. General view of the experimental upland field (100 DAS Stage)

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The effect of varieties and stubble management was significant for chlorophyll content of lentil.

While, the effect of lentil varieties was found to be significant on relative water content at 60DAS and it was non-significant at 30DAS. The relative water content at 60DAS was found significantly higher in DPL15 compared to DPL62. The chlorophyll content and RWC at all growth stages were found significantly higher under mulching followed by 40cm stubble height (Table 3).

Table 3. Physiological parameters of lentil in upland

Treatments Chlorophyll content (mg/g) fresh wt. RWC (%)

30 60 90 30 60

Lentil variety

DPL 62 1.62 1.71 1.67 67.88 68.57 DPL 15 1.83 1.93 1.77 67.14 75.19 Sem 0.03 0.02 0.03 1.18 1.47

CD at 5% 0.09 0.05 0.07 NS 4.18

Tillage

CT-ZT 1.78 1.84 1.66 66.86 68.17 MT-ZT 1.69 1.83 1.71 67.99 72.34 ZT-ZT 1.71 1.80 1.79 67.69 74.14 Sem 0.04 0.02 0.03 1.44 1.80

CD at 5% NS NS 0.09 NS 5.12

Rice stubble management

Mulching 1.80 2.03 1.79 74.98 77.25 Removal 1.58 1.58 1.59 61.10 68.85 20cm 1.75 1.80 1.73 65.11 70.21 40cm 1.78 1.89 1.77 68.86 71.22 Sem 0.04 0.02 0.04 1.66 2.08

CD at 5% 0.13 0.07 0.10 4.74 5.91

The effect of varieties was significant on pods per plant and seed yield whereas it was non – significant on seeds per plant and test weight. The effect of different tillage practices was found non-significant on the seed yield of lentil. However, the effect of residue management practices significantly influenced the yield attributes and yield of lentil. Mulching recorded significantly higher values of yield attributes and yield followed 40cm stubble height compared to residue removal (Table 4).

Table 4. Yield and yield attributes at lentil harvest in upland

Treatments Seeds/plant pods/plant Test wt. (g/1000 seeds) Seed Yield (t/ha) Lentil variety

DPL 62 1.26 22.20 22.23 0.46 DPL 15 1.24 21.34 22.19 0.41 Sem 0.02 0.25 0.18 0.01

CD at 5% NS 0.73 NS 0.03

Tillage

CT-ZT 1.20 22.58 22.38 0.45 MT-ZT 1.29 22.66 22.76 0.43 ZT-ZT 1.26 20.08 21.49 0.43 Sem 0.02 0.31 0.23 0.01

CD at 5% 0.06 0.89 0.64 NS

Mulching 1.23 26.49 22.81 0.55 Removal 1.12 15.15 20.96 0.33 20cm 1.19 22.32 21.89 0.43 40cm 1.44 23.12 23.18 0.43 Sem 0.03 0.36 0.26 0.01

CD at 5% 0.07 1.03 0.74 0.04

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All the treatments had non-significant effect on soil bulk density at different depths. Water holding capacity (WHC) was significantly influenced by the rice stubble management, whereas lentil variety and tillage practices had non-significant effect on WHC. On the other hand, infiltration rate (IR) was significantly influenced by the tillage and rice stubble management whereas, variety had non-significant effect. Among the different stubble management practices, mulching recorded significantly higher WHC and IR followed 40cm stubble height (Table 5).

Table 5. Soil physical parameters at lentil harvest in upland Treatments Bulk Density (g/cm³)

Water holding capacity WHC (%)

Infiltration rate IR (cm/hr) 0-15 cm 15-30 cm 30-45 cm

Lentil variety

DPL 62 1.16 1.24 1.29 48.03 4.16 DPL 15 1.16 1.25 1.28 47.46 4.09 Sem 0.01 0.01 0.01 0.69 0.04

CD at 5% NS NS NS NS NS

Tillage

CD at 5% NS NS NS NS 0.13

CD at 5% 0.02 NS NS 2.78 0.15

Table 6. Soil microbial parameters at lentil harvest in upland

Treatments

Soil organic carbon (%) Dehydrogenase activity (µg/g/hr)

0-15 cm

Soil Microbial Biomass Carbon (µg C / g dry soil)

0-15 cm 0-5

cm

5-10 cm

10-15 cm Lentil variety

DPL 62 1.57 1.52 1.42 2.27 75.83 DPL 15 1.53 1.52 1.39 2.12 76.39 Sem 0.03 0.01 0.04 0.06 0.82

Tillage

CD at 5% NS 0.05 NS NS 2.87

CD at 5% 0.10 0.06 NS 0.26 3.31

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The soil available N and P at different depths were all non-significant with lentil variety, tillage and stubble height management. The SOC at different soil depth did not show any particular trend due to various treatments. In general, the SOC content was relatively higher at surface followed by sub- surface layers. The microbial processes i.e., soil microbial biomass carbon and dehydrogenase activities were significantly affected only by tillage and stubble management. Among the residue management practices, mulching recorded significantly higher DHA and SMBC followed by 40 cm stubble height compared to residue removal (Table 6).

The crop faced moisture stress in upland situation in-spite of the residue management and adoption of conservation tillage systems. Life-saving irrigation with about 0.2 cm water in each plot was given whenever the plants showed wilting symptoms (around 28% moisture content) depending upon rainfall to save the crop. From the graphical representations, it showed that MT-ZT under mulched plot, maintained higher moisture content compared to plots where residue is removed (Fig 4a, 4b). Moisture content under different residue maintained plot were found to be highest under mulched plots followed by 40cm and 20cm stubble height at different stages of the crop (Fig 4c, 4d, 4e).

Fig 4a. Effect of tillage on SMC in mulch plots (0-5 cm) Fig 4b. Effect of tillage on SMC in residue removal plots (0-5 cm)

Fig 4c. Effect of residue management on SMC (MT-ZT at 0-5cm) Fig 4d. Effect of residue management on SMC (MT-ZT at 5-10 cm)

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Fig 4e. Effect of residue management on SMC (MT-ZT at 10-15 cm)

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Study 2

Manipulation of soil moisture through plant type, residue management and balanced nutrition for successful lentil production in lowland land rice fallow (Low land, occasional moisture stress at vegetative stage/flowering stage)

The performance of early duration HYV variety shahsarang 1 was better giving higher grain yield of about 5.02 t/ha compared to the local variety Mendri (3.63 t/ha).

Table 7. Performance of medium and long duration rice varieties in lowland under optimum management

Variety Tillers/m² Panicle/

m²

Grain Yield (t/ha)

Straw yield ( (t/ha)

Harvest Index

Panicle weight (g)

Test wt. (g)

Duration (Days)

Shahsarang 1 (HYV, medium height)

260 250 5.02 7.65 0.396 5.23 23.86 144

Mendri

(local, tall) 195.66 190.66 3.63 12.06 0.231 4.06 25.41 154

The effect of rice varieties had non-significant effect on lentil plant stand, height, yield attributes and yield. The lentil yield was not significantly influenced by the lentil varieties. The rice stubble management practices significantly influenced the pods per plant and seed yield of lentil. There was 48 % and 29.2 % enhancement in seed yield of lentil due to 40 and 20cm stubble heights compared to residue removal, respectively (Table 8).

Fig 5. View of the experimental field with tall and short varieties in lowland condition (90DAS)

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Fig 7. Performance of IPL 406 (Medium duration 133 days with high biomass) under different stubble management Fig 6. Performance of DPL 81 (Early duration 127 days with high biomass) under different stubble management

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Table 8. Yield and Yield attributes of lentil as influenced by treatments in Lowland

Treatments No. of plants in sq.

m

Plant height (cm)

Seeds/pod pods/plant Test wt.(g/1000 seeds)

Seed Yield (t/ha) Rice variety

Shahsarang-

1 162.50 40.70 1.42 43.23 28.06 1.38 Mendri 155.11 39.06 1.49 42.49 28.10 1.29 Sem 7.59 0.62 0.03 0.97 0.12 0.03

CD at 5% NS NS NS NS NS NS

Lentil variety

DPL 81 161.22 38.96 1.59 51.19 21.47 1.55 IPL 406 156.39 40.80 1.32 34.54 34.69 1.12

Sem 7.59 0.62 0.03 0.97 0.12 0.03

CD at 5% NS 1.82 0.09 2.84 0.36 NS

Removal 138.08 36.49 1.42 38.40 27.98 1.06 20cm 157.75 40.27 1.46 43.76 28.02 1.37 40cm 180.58 42.88 1.49 46.43 28.24 1.57

Sem 9.29 0.76 0.04 1.19 0.15 0.04

CD at 5% 27.26 2.23 NS 3.48 NS 0.11

The various treatments had non-significant effect on soil bulk density at different depths except for the rice stubble management at 0-15cm depth of soil. WHC and IR were significantly influenced by the rice stubble management, whereas lentil varieties and rice varieties had non-significant effect on WHC. Among the different stubble management practices, 40cm stubble height recorded significantly higher WHC and IR followed 20 cm stubble height when compared to residue removal (Table 9).

Table 9. Soil physical parameters at lentil harvest as influenced by treatments in lowland Treatments Bulk Density(g/cm³) WHC (%) IR (cm/hr)

0-15 cm 15-30 cm 30-45 cm Rice variety

Shahsarang-1 1.11 1.18 1.27 55.41 3.17 Mendri 1.10 1.18 1.27 54.87 3.24 Sem 0.00 0.01 0.01 0.22 0.05

Lentil variety

DPL 81 1.11 1.17 1.28 55.41 3.19 IPL 406 1.11 1.19 1.27 54.87 3.23 Sem 0.00 0.01 0.01 0.22 0.05

Rice stubble height at harvest

Removal 1.13 1.20 1.27 53.22 2.86 20cm 1.09 1.18 1.26 55.14 3.30 40cm 1.10 1.17 1.28 57.05 3.47 Sem 0.00 0.01 0.01 0.26 0.06

CD at 5% 0.01 NS NS 0.77 0.19

The soil available N at 0-15 and 30-45 cm found significant with stubble height management. The soil available P at different depths and pH were all non-significant with lentil varieties, rice varieties and stubble height management (Table 10).

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Table 10. Soil chemical parameters at lentil harvest as influenced by treatments in lowland

Treatments N (kg/ha) P (kg/ha)

pH (0-15 cm) 0-15 cm 15-30 cm 30-45 cm 0-15 cm 15-30 cm 30-45 cm

Rice variety

Shahsarang-1 273.08 190.55 92.20 11.64 8.90 6.58 4.59 Mendri 270.44 187.59 95.72 11.76 8.91 6.49 4.66 Sem 3.37 3.63 1.53 0.15 0.07 0.07 0.04

CD at 5% NS NS NS NS NS NS NS

Lentil variety

DPL 81 277.08 190.14 92.31 11.56 8.83 6.45 4.62 IPL 406 266.43 188.00 95.60 11.84 8.98 6.62 4.64 Sem 3.37 3.63 1.53 0.15 0.07 0.07 0.04

CD at 5% NS NS NS NS NS NS NS

Rice stubble height at harvest

Removal 267.80 188.92 94.69 11.63 8.77 6.43 4.60 20cm 273.86 189.73 93.70 11.82 9.05 6.53 4.63 40cm 273.61 188.55 93.48 11.65 8.90 6.64 4.65 Sem 4.13 4.45 1.87 0.18 0.08 0.08 0.05

CD at 5% 12.11 NS 94.69 NS NS NS NS

The SOC at different soil depth did not show any particular trend due to various treatments except it was significant with rice stubble management at 0-5cm depth of soil. In general, the SOC content was relatively higher at surface layer followed by sub-surface layers. There was no significant effect of different treatments on dehydrogenase activity. The microbial process i.e., soil microbial biomass carbon (SMBC) was significantly affected by lentil varieties and stubble management.

Among the residue management practices, 40 cm stubble height recorded significantly higher SMBC followed by 20 cm stubble height compared to residue removal.

Table 11. Soil microbial parameters at lentil harvest in lowland

Treatments Soil organic carbon (%) DHA (µg/g/hr) 0-15 cm

SMBC (µg C / g dry soil) 0-15 cm 0-5 cm 5-10 cm 10-15 cm

Rice variety Shahsarang-1

2.22 2.07 2.02 1.99 156.47 Mendri

2.17 1.98 1.98 2.17 157.07 Sem 0.05 0.03 0.03 0.07 1.34 CD at 5%

NS NS NS NS NS

Lentil variety

DPL 81 2.18 2.01 1.97 2.03 153.20 IPL 406 2.22 2.04 2.04 2.12 160.35 Sem 0.05 0.03 0.03 0.07 1.34 CD at 5%

NS NS NS NS 3.92

Rice stubble management Removal

2.07 2.02 2.01 1.96 151.36 20cm

2.22 2.01 1.93 2.10 159.30 40cm

2.30 2.04 2.06 2.18 159.66 Sem 0.06 0.04 0.04 0.08 1.64 CD at 5% 0.17 NS NS NS 4.81

Soil moisture status in lentil field was recorded at regular interval from sowing up to harvest.

Irrespective of treatments, retention of 40 cm stubble height recorded higher soil moisture followed

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by 20 cm stubble height at 0-5, 5-10 and 10-15 cm depths. The lowest soil moisture content was observed under control (residue removal) at all the growth stages.

Fig 8. Graphical representation soil moisture in lowland condition as influenced by rice, lentil varieties and stubble management practices at different depths

Summary

• The lentil variety DPL 81 gave significantly higher Seed yield compared to IPL406 in lowland.

• Retention of 40 cm stubble height in both upland and lowland and mulching in upland maintained higher soil moisture status and organic carbon.

• All the nutrients and soil organic carbon were higher at 0-5cm and lower in deeper layers. BD was higher in lower layers.

• Water holding capacity and infiltration rate were significantly higher under mulching and 40 cm stubble height in upland/lowland.

• Soil microbial biomass carbon was almost double in lowland soil than in upland irrespective of treatments.

• Lentil productivity in upland were only about 30% of lowland due to severe moisture stress (RWC< 70%)

• Retention of 40 cm rice stubble height resulted almost 50% yield enhancement in lowland and mulching resulted 20 % yield enhancement in upland for lentil.