Scientific bases and correct use of organic fertilizers. The effect of organic and inorganic fertilizers on grain yield. Summary of findings and technological significance. This is in solid form and can be spread into paddy soils applied with rice straw or other organic fertilizers to speed up their decomposition. Azolla microphylla has greater sporulation in soils previously applied with chicken manure or vermicast than other organic fertilizers applied basally.
Soil pH decreases slightly when organic fertilizers are continuously applied due to the release of carbonic acid into the soil due to the decomposition of the applied organic C materials. Soil pH trend as affected by the average effect of different organic fertilizers alone (OB), inorganic fertilizers alone (half rate or HR and full rate or FR) and in combination with half (OBHR) or full (OBFR) recommended amount of NPK. Soil organic matter trend as affected by the average effect of different organic fertilizers alone (OB), inorganic fertilizers alone (HR and FR) and in combination with half (OBHR) or full (OBFR) recommended amount of NPK.
The application of organic fertilizers results in higher soil carbon exchange capacity (CEC) indicating a higher absorption of the nutrient released or available from organic or inorganic fertilizers. Rice straw with or without inoculant has lower BD among other organic fertilizers applied, with full NPK rate than with half NPK rate. The application of organic fertilizers has a high emission of greenhouse gases due to the high carbon content and causes the formation of methane gas when it reacts with irrigation water.
Grain yield is low when only organic fertilizers are applied except those applied with chicken manure which have a yield comparable to the inorganic fertilizers especially in the dry seasons (Table 1).
GRAIN YIELD AS AFFECTED BY ORGANIC AND INORGANIC FERTILIZERS
Yield Responses to Organic Fertilizer Versus Native Soil Nutrients and Applied Inorganic Fertilizer (1999 WS - 2001 DS). Consistent or sustainably high grain yield is achieved by mixing supplemental rice straw with various inorganic nutrients (Table 3). Yield responses to different organic and inorganic fertilizers applied alone or in combination during 36 crop seasons.
The grain yield of organically grown rice plants is lower than those using NPK level (Figure 5), especially during dry periods. Adjusted grain yield (Mg/ha) of PSB Rc 28 as affected by different integrated fertilizer managements and strategies under Maligay conditions. Average seasonal and annual grain yield of PSB Rc 82 under the influence of different organic fertilizers applied alone or in combination with half and full recommended amount of NPK.
Comparable yield of all organic fertilizers used with that of inorganic fertilizers occurred every 8 years, but only in the wet season. Grain yield was sustainably higher with any of the tested organic fertilizers with full NPK dose or half NPK fertilizer dose. Average yield increases of 23.7 to 29.8% are achieved when organic fertilizer is applied together with half the NPK dose.
Average yield increases of 25.7 to 33.1% are achieved when applying organic fertilizers at full NPK rate. Rice straw, chicken manure and green manure as organic fertilizers exceeded the target yield of 4 t/ha for solo organic-based nutrient management (OBNM) for both seasons, but only chicken manure exceeded the target yield in the dry season (Figure 7) . Consistently, a high average yield was achieved when organic fertilizer is combined with inorganic fertilizer at either half or full NPK recommended amount.
Average seasonal grain yield of PSB Rc 82 as affected by different organic fertilizer applied alone (b) or in combination with half and full recommended amount of NPK. Average yield from 2004 to 2021 DS due to different use of organic leaf supplements for paddy rice. Average yield from 2004 to 2021 due to different use of only organic fertilizers and combined with half or full NPK rate for paddy rice.
SUMMARY OF FINDINGS AND TECHNOLOGY IMPORTANCE
The efficiency of nutrient management based on organic packaging is reflected in a sustainably high grain yield. Incorporating rice straw into the soil at least 30 days before sowing seeds or planting seedlings as a pre-crop soil health maintainer. Grain yield was observed to be the highest when organic fertilizer or rice straw with chicken manure was applied before applying the full recommended amount of NPK according to plant nutrient requirements at a given stage and even higher than after improved conventional nutrient management.
Other OBNM with rice straw added with either chicken manure or vermicast before transplanting, followed by azolla application on days after transplanting also gave yield higher than the target rice yield of sustainable 4t/ha (both in wet or dry seasons) after the OBNM.
PACKAGING COMPONENTS FOR IRRIGATED RICE
Hybrid rice is also responsive to the packaged component of OBNM and has achieved the target yield of 4 t/ha for organic-based rice in both seasons. Combined rice achieved the target yield of 4 t/ha only in the wet season, but hardly achieved it in the dry season. A sustainable yield higher than 5 t/ha can be achieved by reincorporating organic manure, especially using rice straw as a soil conditioner before rice planting, and after applying nutrients based on plant demand after transplanting rice.
A sustainable average of 4 t/ha can be achieved by following the packaged OBNM: incorporation of rice straw + chicken manure or vermicast plus Azolla as the alternative organic N source for the rice plants after transplanting (Figure 10). For farmers without finances, OBNM can be followed at half the recommended NPK rate and can still reach an average of 4t/ha. Average annual yield (t/ha) of rice in response to organic and inorganic-based nutrient management.
PACKAGED NUTRIENT MANAGEMENT OPTIONS FOR SUSTAINABLE GRAIN YIELD AND SUSTAINING SOIL HEALTH AND PRODUCTIVITY
Ideal for (1) more receptive and more progressive farmers; (2) those willing to compost and recycle their own agricultural waste as soil improvers and plant nutrients. Rice straw should be processed through dry land preparation at least 30 days before transplanting to avoid high greenhouse gas emissions. At the second harrowing, or 14 days before transplanting, apply air-dried chicken or carabao manure.
Muriate of potash can be eliminated from the recommendation after 3 years of rice straw application. Phosphorus can also be eliminated after 3 years of manure application, but must be reapplied as needed based on Minus-One Element Technique (MOU) or soil analyses. Ideal for progressive farmers who are more willing to follow the judicious use of inorganic fertilizers.
LCC-based N application from 7 DAT reading to early flowering: Apply 23kg N/ha each reading below LCC 3. Optionally apply half a bag of urea/ha when at least 15% of the panicle is exercised 4. Ideal for ( 1) those who cannot purchase the full inorganic NPK recommended rate per hectare but have enough farm waste to use as nutrients and soil conditioners and (2) those willing to compost and recycle their own farm waste as soil conditioners and nutrients for the plants.
At the second harrowing or 14 days before planting, apply 500 kg/ha of air-dried chicken or carabao manure. Muriate of potassium chloride can be removed from the recommendation after 3 years of application to rice straw. Phosphorus can also be removed after 3 years of fertilizer application, but should be reapplied as needed according to MOET or soil analysis.
Are soil macronutrients depleted or built up with long-term application of organic fertilizers in rice soils? Will pure non-fossil fuel-based nutrient management be a practical alternative source for irrigated lowland rice production? Nutrient mineralization, P and K availability in soil due to the application of different applied fertilizers under flooded conditions.
Will a purely fossil fuel-based nutrient management be a viable alternative resource for lowland irrigated rice production? Evaluation of organic N sources to further increase yield in an organic-based nutrient management in irrigated irrigated soils. Re-evaluation of critical reading of leaf color chart in an organic-based nutrient management in paddy rice.
Comparative effect of chicken manure and effective microorganism-based bokashi as inoculant to rice straw decomposition. Screening and selection of different Azolla spp as potential improver for acid and saline rice soils. Economic Analysis of Rice Straw Management Alternatives and Understanding Farmers' Choices (James D & Francisco HA, Eds).
Yield responses of rice varieties to different top dressings in an organic-based nutrient management. Soil microbial community functional structures and enzyme activities in sandy soil after eight organic years. Effects of long-term compost application and water management on rice and maize in favorable lowland rainfed fields.
Thank you for the assistance of the following researchers who have worked on the long-term use of organic and inorganic fertilizers in rice soils: Annie E. Thank you to the Executive Directors, Deputy Executive Directors, Division Heads, and Program Leaders who supported the implementation of the studies, and to the administrative assistants who facilitated the needs of the projects: Geradine Rimocal, Eloisa Tolentino, Arlene Sevilla and Ermina Ramos. No part of this manual may be reproduced or translated in any form without the written permission of the copyright holder, except quotations and references, which will be properly attributed to this publication.
