Evaluating the Soil Quality Indicators in Various Yield Zones of Pulses in Tamil Nadu, India

Background: In recent years, there is growing demand for pulses in Tamil Nadu and the government has implemented various schemes and programmes to promote cultivation. However, the evaluation and categorization of soils for pulse production is crucial in determining the suitability of land for pulse cultivation and offer improvement through the adoption of improved crop management practices. Methods: A systematic soil quality assessment survey was taken up during 2020-2022 in the major pulse growing blocks of Virudhunagar district viz., Sattur, Aruppukottai and Thiruchuli based on past ten years yield data and it was classified into three categories viz., low yielding ( less than 400 kg ha-1), medium (400 to 700 kg ha-1) and high yielding ( greater than 700 kg ha-1) categories. Three hundred samples were collected from these zones. Results: The positive effects of soil physical, chemical, and biological qualities on the yield of pulse crops were justified through the yield data of the high yielding zone which ranged from 769 to 989 kg ha-1 with an average pulse yield of 880 kg ha-1. This may be attributed to more favourable soil physical environment in terms of soil texture (sandy clay loam), higher mean percentage of water stable aggregates (51%) and a favourable pH of 7.52. These parameters coupled with lower bulk density (1.23 Mgm-3), optimum infiltration rate (1.76 cm hr-1) and maximum mean organic carbon status (1.38 mg kg-1) contributed to higher range of soil cation exchange capacity (28.7 to 47.2 cmol p+ kg-1). In addition, the presence of avilable nitrogen and phosphorus, potassium, sulphur and availability of mean micronutrient contents viz., DTPA iron and DTPA zinc resulted in better quality of these soils contributing to maximum pulse productivity in this zone. Soil respiration rate with mean respiration rate of 4.48 mg CO2 kg-1 d-1 in high yield category compared to that of 2.34 mg CO2 kg-1 d-1 in low yield category, which is well correlated with better soil organic matter content in the former than the latter group of soil. Therefore, this study formulates a clear understanding of the variations in soil quality parameters for adopting efficient nutrient management practices towards obtaining maximum productivity of pulse crops.