Responses of soil organic carbon, aggregate diameters, and hydraulic properties to long‐term organic and conventional farming on a Vertisol in India

Abstract

Organic matter management can improve soil structural properties. This is crucial for agricultural soils in tropical regions threatened by high rainfall intensities. Compared to conventional farming, organic farming is usually deemed to increase organic carbon and improve soil structural properties such as stability and permeability. However, how much, if any, buildup of organic carbon is possible or indeed occurring also depends on soil type and environmental factors. We compared the impact of seven years of organic farming (annually 13.6 t ha−1 of composted manure) with that of conventional practices (2 t ha−1 of farmyard manure with 150–170 kg N ha−1 of mineral fertilizers) on soil structural properties. The study was conducted on a Vertisol in India with a two‐year crop rotation of cotton soybean wheat. Despite large differences in organic amendment application, organic carbon was not significantly different at 9.6 mg C g−1 on average in the topsoil. However, the size distribution of water‐stable aggregates shifted toward more aggregates <137 μm in the organic systems. Cumulative water intake was lower compared to the conventional systems, leading to higher runoff and erosion. These changes might be related to the lower pH and higher exchangeable sodium in the organic systems. Our results indicate that higher application of organic amendments did not lead to higher soil organic carbon and associated improvement in soil structures properties compared to integrated fertilization in this study. Chemical properties may dominate soil aggregation retarding the uptake and integration of organic amendments for sustainable agricultural intensification in tropical, semiarid climates.

Land degradation and development in India: Status quo, challenges and opportunities

“…In addition to soil salinization, studies investigated the impacts of the application of organic amendments on soil carbon, structure (Schweizer et al, 2022), crop yield, and greenhouse gas emissions (Reddy et al, 2023). Schweizer et al (2022) compared the impact of 7 years of organic farming (annually 13.6 t ha À1 of composted manure) with conventional practices (2 t ha À1 of farmyard manure with 150-170 kg N ha À1 of mineral fertilizers).…”

“…In addition to soil salinization, studies investigated the impacts of the application of organic amendments on soil carbon, structure (Schweizer et al, 2022), crop yield, and greenhouse gas emissions (Reddy et al, 2023). Schweizer et al (2022) compared the impact of 7 years of organic farming (annually 13.6 t ha À1 of composted manure) with conventional practices (2 t ha À1 of farmyard manure with 150-170 kg N ha À1 of mineral fertilizers). The results of this study find that higher application of organic amendments did not lead to higher soil organic carbon and associated improvement in soil structural properties compared to integrated fertilization in this study.…”

Architecture of soil microaggregates: Advanced methodologies to explore properties and functions

“…(2019). Hence, applying DIA allows quantifying aggregate sizes in dry, wet, and dispersed states at a resolution of a few µm up to the mm range (Table 1; Felde et al., 2021; Schweizer et al., 2022).…”

Carbon to nitrogen stoichiometry of organic amendments influences the improvement of aggregate stability of a cropping vertisol

“…Soil aggregates support many crucial functions, including water and nutrient cycling, storing carbon, and providing a habitat for plant roots and microbes (Creamer et al., 2022; Oades, 1984). Vertisols, soils with a high content of shrinking‐swelling clays, cation exchange capacity and fertility, are one of the most productive soils when properly managed (Schweizer et al., 2022). Recent studies have proved that the type of clay minerals plays an essential role in the stabilization of the soil macroaggregates (Bravo‐Garza et al., 2009).…”