Sathyashankara Sharma

Effects of Conjunctive Use of Organic and Inorganic Sources of Nutrients on Soil Quality Indicators and Soil Quality Index in Sole Maize, Maize + Soybean, and Sole Soybean Cropping Systems in Hot Semi-arid Tropical Vertisol

The soils in the hot semi-arid tropical (SAT) regions generally have low organic matter and nutrient reserves. Soil-management problems in these soils primarily occur because of poor physical conditions and inadequate drainage through excess runoff, finally resulting in poor crop growth. Hence, the present investigation was conducted to study the long-term impact of conjunctive nutrient use treatments on soil quality indicators and soil quality indices under three cropping systems: (i) sole soybean, (ii) soybean + maize, and (iii) sole maize cropping systems at the Indore Centre of the All-India Coordinated Research Project for Dryland Agriculture (AICRPDA) using Navjot and JS-335 as cultivars of maize and soybean, respectively. In 2005, the soil quality assessment study under this experiment was undertaken after 8 years of experimentation. Soil quality assessment was done by identifying the key indicators using principal component analysis (PCA) and linear scoring technique (LST). Soil quality indices (SQI) and relative soil quality indices (RSQI) were also computed. Results revealed that most of the soil quality parameters were significantly influenced by the conjunctive nutrient management treatments. The common key indicators that emerged in all the treatments were pH, organic carbon (OC), exchangeable magnesium (Mg), available zinc (Zn), copper (Cu), manganese (Mn), and boron (B). The soil quality indices across the management treatments under sole maize system varied from 1.70 to 2.40 and application of 20 kg nitrogen (N) (compost) + 20 kg N through urea as top dressing emerged as a one of the most superior treatments with SQI value of 2.40. The soil quality indices in maize + soybean system varied from 1.12 to 1.47 and application of 20 kg N (compost) + 20 kg N through urea + azotobacter at 2 kg ha−1 proved to be significant with the greatest SQI value of 1.47. In the case of the sole soybean system, the SQI varied from 1.21 to 1.61. After considering all the systems together, the average best performance SQI score (ABP-SQI score) was computed, which varied from 1.14 to 1.56. The greatest value was recorded in the treatment with 20 kg N (compost) + 20 kg N (gliricidia) + 10 kg N (urea). The quantitative relationship developed in this study between mean soybean and maize yields (Y) and RSQI values (X), irrespective of the management treatments, could be quite useful to predict the yield quantitatively with respect to a given change in key indicators for these rainfed Vertisols.

Production Potential, Economics and Nutrient Uptake of Sesame (Sesamum indicum) Under Different Organic Nutrient Management Practices in Rainfed Region of Rajasthan

A field experiment was conducted during the kharif season 2010 to 2012 at Dryland Farming Research Station, Bhilwara (Rajasthan) to evaluate the effect of organic nutrient management practices on production, economics and nutrient uptake of sesame (Sesamum indicum). Application of enriched compost @ 4 t/ha along with biodynamic manure (BD) 500 @ 62.5 g/ha in 40 L water and BD 501 @ 2.5 g/ha in 40 L water with PSB and Azotobacter produced higher growth and yield attributes, yield (788 kg/ha) and economics (3.84) of sesame. On average, significant increase in seed yield due application of enriched compost @ 4 t/ha + BD 500 + BD 501 + Azotobacter + PSB was 18.5, 28.8 and 14.2% over the application of FYM @ 8 t/ha + Azotobacter + PSB, vermicompost @ 4 t/ha + Azotobacter + PSB and enriched compost @ 2 t/ha + Azotobacter + PSB, respectively. Biodynamic manure 500 and 501 in combination with enriched compost @ 4 t/ha gave an additional yield of 98 to 259 kg/ha as compared to sole application of enriched compost, FYM or vermicompost to sesame. Application of enriched compost @ 4 t/ha + BD 500 + BD 501 + Azotobacter + PSB also resulted in maximum net return (52704/ha), B: C ratio (3.84) and also had significant effect on uptake of nitrogen, phosphorus and potash by sesame.

Soil Quality Assessment under Restorative Soil Management Practices in Soybean (Glycine Max) after Six Years in Semi-Arid Tropical Black Lands of Central India

ABSTRACT Vertisol soils of central India are heavy in texture, with high clay content and low organic matter. These soils are prone to degradation and the soil loss is due to poor management practices including excessive tillage. Based on a long-term study conducted for improving the quality of these soils, it was found that management practice such as low tillage (LT) + 4 t ha−1 compost + herbicide (Hb) recorded significantly higher organic carbon (OC) (6.22 g kg−1) and available N (188.5 kg ha−1) compared to conventional tillage (CT) + recommended fertilizer (RF) + off-season tillage (OT) + hand weeding (HW) (OC: 4.71 g kg−1, available nitrogen (N) (159.3 kg ha−1). Among the physical soil quality parameters, mean weight diameter (MWD) was significantly higher under LT + 4 t ha−1 straw + Hb (0.59 mm). The practice of LT + 4 t ha−1 straw + HW recorded significantly higher microbial biomass carbon (MBC) (388.8 μg g−1). The order of key indicators and their contribution towards soil quality was as follows: OC (29%) >, MBC (27%) > available zinc (Zn) (22%) > MWD (9%) > available boron (B) (8%), > dehydrogenase activity (DHA) (5%). The order of the best treatment which maintained soil quality index (SQI) values reasonably good (>1.5) was as follows: LT + 4t ha−1 compost + HW (1.65) > LT + 4 t ha−1 compost +Hb (1.60) > LT + 4t ha−1 straw + HW (1.50). Hence, these treatments could be recommended to the farmers for maintaining higher soil quality in Vertisols under soybean system. Correlation studies revealed stronger relationship between key indicators like OC (R2 = 0.627), MBC (R2 = 0.884), available Zn (R2 = 0.739) and DHA (R2 = 0.604) with Relative Soil Quality Index (RSQI). The results of the present study would be highly useful to the researchers, farmers and land managers.