Organic substitution in fertilizer schedule: Impacts on soil health, photosynthetic efficiency, yield and assimilation in wheat grown in alluvial soil

Parijat Saikia , Satya Sundar Bhattacharya, K.K. Baruah - Agriculture, Ecosystems and Environment 203 (2015) 102–109

Farm Table says:

This paper was conducted in a very climate specific area and constant tropical environment. It does not clearly state of how it will be beneficial for those who have the exact opposite temperate climate.

The Overview of Organic Substitution:

The soil is considered as the primary reservoir of organic carbon (C) in terrestrial ecosystems. The amount of carbon in a terrestrial ecosystem is about 3170 Gt and nearly 80% (2500 Gt) of this amount is found in soil. Soil organic carbon (SOC) depletion is potentially related to yield decline of rice and wheat crops. However, carbon sequestration potential can be changed by many factors such as climate and soil conditions, cropping systems, management including tillage and balanced fertilization.

Management of soil in an agricultural ecosystem is considered to be important in maintaining soil health and soil carbon storage. Various combinations of inorganic fertilizers, farmyard manure, and crop residues were assessed in a wheat crop grown in alluvial soil for two consecutive years. Several attributes like soil organic carbon (SOC), soil total carbon (TC), soil carbon storage (SCS), soil moisture content (SMC), easily mineralizable N along with above ground and below ground biomass were studied, photosynthetic rate and grain yields during various growth stages.

The major objective of this study was to evaluate the effects of integrated nutrient management schemes on soil C stock and crop improvement. Moreover, we were interested in recognizing the overall impact of substitution of chemical fertilizers with organic amendments in regard to soil quality and productivity.

Discussion of Results:

• Wheat biomass yield was increased with application of organic amendments

• carbon assimilation by plant photosynthesis during the reproductive stages enhanced with an increment of SOC. about 10.88% and 10.52% organic SCS was recorded in soil depth of 0– 15 cm

• about 11.50% and 12.46% in soil depth of 15–30 cm under 100% NPK + CR + FYM and 80% NPK + CR + FYM treatments, respectively.

• CR and FYM in combination can maintain SOC stock considerably and 80% NPK + CR + FYM substitutes 20% inorganic fertilizer without compromising crop growth and development.

Judicious use of organic and inorganic fertilizer application is essential for efficient soil carbon storage and wheat productivity. Plant photosynthesis plays a crucial role in biomass production and soil organic carbon increment, which also varies with fertilizer management. A combined use of inorganic fertilizer along with CR and FYM is a good alternative to enhance soil carbon stock. FYM and CR application with two different levels of inorganic fertilizer addition showed that use of 80% NPK + CR + FYM is preferable for carbon storage enhancement. Addition of organic amendments with 100% and 80% NPK levels significantly improved plant carbon fixation capability or photosynthesis along with LAI.

Moreover, a significantly high correlation between SOC and plant photosynthesis, plant leaf biomass, root biomass and LAI was observed in the present study. Therefore, plant biomass yield may play an important role in enhancing SOC storage.

2015 - India - Parijat Saikia , Satya Sundar Bhattacharya, K.K. Baruah - Agriculture, Ecosystems and Environment 203 (2015) 102–109
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