Developing causal loop diagrams for the perusal of soil health in agricultural practices – A case study of rice nursery cultivation practices in India

Abstract

CONTEXTSoil is a key component of the agriculture–livestock–forestry nexus. However, it has been reported that 40% of the agricultural soil is being degraded globally; in India, 70% of the agricultural soil is undergoing degradation despite various efforts to improve soil health. Hence, the current study takes a paradigmatic shift by applying the approach of systems thinking for understanding soil health. OBJECTIVEThis study aims to present an alternative methodology to study the impact of agriculture practices on soil health with a systems approach. METHODSA practice of soil parching for rice nursery cultivation, called raab, representing the agriculture–livestock–forestry nexus, was taken as a case study. The study included field visits to rice farms in Maharashtra, India, soil sample collection at three stages of raab practice, and soil samples from non-raab fields. Thirty-one soil samples were tested for four properties: pH, electrical conductivity, available potassium, and permanganate oxidizable carbon (POXC) in raab and non-raab nursery fields. Further, a causal loop diagram of the soil ecosystem was developed based on farmer interactions, soil testing results, and literature to identify the key system archetype in this case study. RESULTS AND CONCLUSIONStatistical analysis of the results showed a significant difference in soil properties at different stages of cultivation and in comparison to the control group. The mean pH of raab fields had increased due to the raab practice from 5.76 to 7.01, and the mean electrical conductivity increased from 0.218 dS/m to 0.745 dS/m. The mean available potassium increased from 229.9 kg/ha to 1239 kg/ha in the raab fields, while direct nursery fields had a mean of 487 kg/ha at the time of sowing. The mean POXC increased from 0.02 to 0.04 mol of MnO4− reduced. The causal loop diagram developed had 17 loops, 15 of which were favorable-reinforcing loops, and two were unfavorable-balancing loops. The system archetype of “Limits to growth” was identified in this study, based on which recommendations are suggested for maintaining soil health. SIGNIFICANCEThe systemic approach aids in decision-making regarding sustainable agriculture practices considering soil ecological processes with judicious use of resources available from the forest and livestock. The direct impact of soil health on five UN Sustainable Development Goals (SDGs) and the indirect impact on seven other SDGs underscores the global significance of the novel approach discussed in this study.