Evaluation of different organic manure of rice productivity and soil chemical indicator in a vertisol

Introduction

 Soil, is a fundamental natural resource supporting a variety of ecosystem functions and services to the benefit of the mankind.  However, the current production process to fulfil the food requirement of everincreasing population, it has been the tremendous pressure on soil ecosystem health to increase the productivity per unit area under indiscriminate use of fertilizer  In such scenario there is a need to evaluate different sources of organic manure that can replace excess use of chemical fertilizer to maximize productivity and sustain soil health with respect to soil nutrient status and factor productivity.

Materials and Methods

The present investigation entitled "Evaluation of different organic manures on rice productivity and soil chemical indicator in a Vertisol" was conducted at STCR field-Instruction cum research farm, College of Agriculture, IGKV, Raipur, (C.G.) during the year 2024-25. The experiment was carried out to study the yield attributes, yield of rice, nutrient uptake, balance factor, productivity, soil chemical indicators and relationship between crop yield and soil chemical indicators as influence by different organic manures. The details of experimental techniques, materials used and methods adopted for treatment evaluation during the course of investigation.

Results and Discussions Yield attributes

Results revealed that both organic manures and the recommended dose of fertilizer (RDF) significantly influenced the total tillers per hill and effective tillers per hill of rice compared to the control. Among the treatments, the maximum total tillers (9.6) and effective tillers (6.5) per hill were recorded under T 2 (RDF), while the minimum values (5.4 and 3.5, respectively) were observed in T 1 (Control). The superior performance of RDF may be attributed to its ability to provide a balanced and readily available supply of essential macro and micro-nutrients, which are critical for key physiological processes in rice. RDF also improves soil physical and chemical properties, enhancing nutrient availability and overall soil fertility.

The comparatively lower performance of organic manures in tiller production may be due to the slow mineralization of organic manures applied to soil, resulting in a delayed and reduced nutrient release, which is insufficient to meet the crop's immediate requirements. These findings are in agreement with the reports of Biswal et al. (2021) [2] , Dhaliwal et al. (2023) [4] and Baghel et al. (2024) [1] in rice.

Note:

The superscript letters signifies that the treatment means with similar letters are at par at 5% level of significance, while the means with different letters are significantly different at 5% level of significance. These letters have been affixed based on CDvalue comparison of treatment means.

As per the data presented in The superscript letters signifies that the treatment means with similar letters are at par at 5% level of significance, while the means with different letters are significantly different at 5% level of significance. These letters have been affixed based on CD-value comparison of treatment means.

The superior performance of RDF can be attributed to the balanced and readily available supply of macro and micronutrients, which promotes longer panicles, higher grain formation, greater panicle weight and improved test weight. In contrast, the relatively lower performance of organic manure treatments is likely due to the slow mineralization of organic materials, resulting in a delayed nutrient release that may not fully meet the crop's nutrient demand during critical stages of panicle initiation and grain development. These findings are in agreement with Jothi et al. (2021) [5] , and Moe et al. (2023) [7] in rice. The observed superiority of RDF in enhancing rice productivity can be attributed to the balanced and readily available supply of essential nutrients, which supports optimal vegetative growth, efficient photosynthesis and assimilate translocation to developing grains. Adequate nutrient availability during critical growth stages ensures a higher number of panicles, better grain filling and improved partitioning of assimilate, reflected in an enhanced harvest index. In contrast, the relatively moderate performance of organic manures is primarily due to the slow mineralization of nutrients. The gradual release of nitrogen, phosphorus and potassium from organic sources often does not coincide with the crop's peak nutrient demand during tillering, panicle initiation and grain filling. Additionally, variability in nutrient content and the higher carbon-to-nitrogen ratio in some organic amendments can temporarily immobilize nutrients, limiting their immediate availability to the plant. Despite this, organic manures play a crucial role in improving soil structure, enhancing microbial activity and maintaining long-term soil fertility, which contributes to sustainable productivity over time. These findings highlight the importance of synchronizing nutrient supply with crop demand. While RDF ensures rapid nutrient availability and immediate yield benefits, organic manures may offer the dual advantage of high productivity and soil sustainability. The study aligns with previous research indicating that balanced fertilization enhances growth and yield attributes more effectively than sole organic amendments, while organic manures support long term soil health and fertility (Paul et [8,10,9,11] . The findings of the present study indicate that nutrient management through different organic manures and RDF had a pronounced effect on the uptake of N, P and K by rice. The superior nutrient uptake observed under RDF (T 2 ) can be attributed to the balanced and readily available supply of essential macro-nutrients, which promotes vigorous vegetative growth, enhanced root development and improved nutrient absorption from the soil. The higher N, P and K uptake under RDF is also a result of better synchrony between nutrient availability and crop demand, ensuring that nutrients are accessible during critical growth stages such as tillering, panicle initiation and grain filling.

In contrast, the comparatively moderate nutrient uptake under organic manures is primarily due to the gradual mineralization of nutrients, which delays their availability to the crop. Nitrogen in organic amendments is released slowly through microbial decomposition, phosphorus may remain in less soluble forms and potassium release can be limited depending on the source and soil characteristics. As a result, nutrient availability during peak demand periods is sometimes insufficient, leading to moderate uptake levels compared to chemical fertilizers. Furthermore, the higher nutrient uptake under RDF not only increases the concentration of N, P and K in plant tissues but also enhances overall biomass and grain production, thereby amplifying total nutrient accumulation. Organic manures, while slower in supplying nutrients, contribute to long-term soil fertility, organic carbon content and microbial activity, which are essential for sustainable crop production.

The observations are in agreement with earlier studies by Choudhary et al. (2009) [3] , Biswal et al. (2021) [2] and Baghel et al. (2024) [1] , which also reported that balanced fertilization improves nutrient uptake, growth and yield in rice. The differences in partial factor productivity among treatments can be attributed to variations in nutrient availability, release patterns and their synchronization with crop demand. Application of the recommended dose of fertilizers ensures readily available nutrients, promoting efficient uptake and higher nutrient use efficiency.

However, higher fertilizer rates may sometimes result in diminishing returns, where additional nutrients contribute less to yield per unit applied. In contrast, organic sources such as FYM, poultry manure and kitchen waste release nutrients more slowly, which can limit their immediate availability during critical crop growth stages. Nevertheless, these organic amendments enhance soil physical, chemical and biological properties, improving long-term nutrient cycling, microbial activity and overall soil fertility. Integrated nutrient management (INM), which combines organic and inorganic sources, can optimize nutrient supply, maintain agronomic efficiency and ensuring sustainable rice production.

To establish the relationship between crop yield and soil chemical indicators

The correlation analysis among soil fertility parameters, crop growth attributes and yield revealed several important relationships. Grain yield and straw yield exhibited very strong and highly significant positive correlations with effective tillers (r=0.97, p<0.001 for both) and total tillers (r=0.94-0.96, p<0.01 to 0.001), indicating that tiller production is a major determinant of rice productivity. Among the soil fertility parameters, available N showed the highest and most significant positive correlation with grain yield (r=0.95, p<0.01) and straw yield (r=0.91, p<0.01), as well as with total tillers and effective tillers. This clearly indicates that available N is the most critical soil factor governing yield performance under the present study, playing a key role in promoting vegetative growth, tiller formation and ultimately higher productivity. Soil Organic Carbon (SOC) exhibited moderate but nonsignificant correlations with grain (r=0.67) and straw yield (r=0.70), indicating its supportive role in soil health over the long term rather than immediate yield response. Available P and K showed weak to moderate, non-significant correlations with growth and yield parameters. Overall, the results emphasize that tiller number and available nitrogen are the most influential factors affecting rice yield, while SOC, P and K contribute more indirectly to crop performance.

Conclusion

The present study concluded that the 100% application of different organic manure did not achieve rice yield as compared to RDF. However, they were effectively sustained the soil nutrient status.  The nutrient uptake and factor productivity of N, P and K were maximized under RDF, while vermi-compost recorded the highest values among the organic treatments.  Organic manures also played a crucial role in maintaining or improving the soil nutrient status (available N, P and K) compared to the initial levels, suggesting their potential to sustain soil fertility over time.  Correlation analysis indicated that soil available nitrogen had the strongest positive relationship with rice yield, identifying it as a sensitive and reliable indicator of soil productivity in this system.  In the present study organic manure applications achieved the good yield, however, it was significantly lower than 100% RDF, this may be because the study is based on one season experiments and the organic manure having potential of slow nutrient release capacity. It may be possible that the continuous field experiment up to at least 3 years may give more clear results about the impact of different organic manures.

References

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