Impact of Integrated Rice-Crayfish Farming on Soil Aggregates and Organic Matter Distribution

Abstract

This study evaluates the effects of a combined rice-crayfish farming model and compares this model with traditional paddy fields. The focus is on soil aggregate characteristics, organic matter content, and also the distribution of soil aggregates. This research was conducted in Qianjiang, Hubei Province. The surface soil samples were collected from two types of arable land: paddy fields (WR) and rice-crayfish fields (CR). We performed an analysis of soil aggregate distribution and organic matter content. Results reveal that the majority of soil aggregates exceed 2 mm in size (≥74.94%). The integrated rice-crayfish farming model significantly enhances the presence of large soil aggregates. And these parameters such as the average weight diameter (MWD), average geometric diameter (GWD), and agglomerate stability (PAD) also increase. Moreover, it mitigates agglomerate fragmentation (WASR). However, the net increase in total soil organic matter due to the integrated farming model remains modest. Organic matter content within the agglomerates follows an initial increase followed by a decrease. The highest content occurs in the 0.25–0.5 mm grain size (D4). When examining the distribution of soil aggregates and organic matter, it becomes evident that organic matter primarily originates from grain sizes larger than 2 mm (≥71.92%). Notably, the rice-crayfish paddy field (CR) exhibits a substantially higher contribution compared to the traditional rice paddy field (WR). This study demonstrates several positive outcomes of the integrated rice-crayfish farming model compared to traditional paddy farming. It promotes the development of larger soil aggregates, enhances the structural integrity of soil aggregates, and improves their mechanical and hydrological stability. Additionally, it marginally increases the organic matter content within each component of soil aggregates. Furthermore, integrated modelling increases the impact of larger soil aggregates on soil organic matter. This improves the quality of the soil and as a result, crop yields are increased. The health of the soil is also improved and this contributes positively to food security.

Spatial Analysis on Resource Utilization, Environmental Consequences and Sustainability of Rice–Crayfish Rotation System in Jianghan Plain, China

“…Additional evidence from our survey indicates that RCR, recognized as an environmentally friendly system, enjoys popularity among both farmers and local governments. The success of this model is rooted in a symbiotic relationship between rice and aquatic animals in one system that enhances the system's overall efficiency due to their interactions to produce a synergistic effect [62,63]. In RCR, paddy fields not only offer crayfish shelter, optimal water temperatures and suitable oxygen levels, but also provide them with a variety of food sources including rice grains, weeds, pests, residual seeds and soil organisms [21,29,64].…”

Effects of Long-Term Rice–Crayfish Coculture Systems on Soil Nutrients, Carbon Pools, and Rice Yields in Northern Zhejiang Province, China

“…This may be attributable to the following reasons. First, the flooding period in our rice-red-claw crayfish systems is about 120 days longer than in other rice-crayfish systems [14,39], and persistently high soil moisture promotes the reductive dissolution of soil iron oxides, which promotes microbial exposure to previously protected iron oxides. It also promotes microbial access to previously protected unstable carbon, thereby increasing carbon loss from the soil [49].…”