N. K. Lenka

Soil-related Constraints to the Carbon Dioxide Fertilization Effect

The significance of CO2 fertilization in increasing net primary production (NPP) and of the underpinning mechanisms is widely recognized. This article focuses on soil resources, particularly availability of plant nutrients (e.g., nitrogen, phosphorus) and water affecting the NPP under enhanced levels of atmospheric CO2. The review of the literature indicates the critical role of N in enhancing NPP at higher than ambient CO2 concentration. Elevated CO2 increases the total N uptake by 3–33% and induces a negative feedback in soil N dynamics. Decrease in tissue N concentration by 10–33%, and increase in the recalcitrant C- fractions in plant biomass results in progressive decline in soil N availability over time and necessitates supplemental application of N. In addition, higher quantity of soil available P is required. Despite a reduction in stomatal conductance and transpiration by about 20–27% at leaf level, these benefits are offset at the ecosystem level by higher water losses through soil evaporation, runoff and a rise in leaf temperature due to physiological forcing. A three-way interaction between atmospheric CO2, soil nutrients and water availability may be the decisive factor to harnessing the benefits of CO2 fertilization effect.

Integrated Nutrient Management to Improve Finger Millet Productivity and Soil Conditions in Hilly Region of Eastern India

Studies on effective integrated nutrient management (INM) modules for marginal landholders of eastern India relying upon crops, such as finger millet (Eleusine coracana L. Gaertn), are lacking. Thus, an experiment was conducted on farmers field for three years (2002−2004) at Malipungar watershed in the Koraput district of Odisha, India, to evaluate various INM combinations and select the most remunerative INM option relative to productivity and profitability of finger millet crop and soil properties. The seven INM treatments consisted of different combinations of Gliricidia green-leaf manure, farmyard manure (FYM), synthetic fertilizers, and bio-fertilizers and compared with farmers practice. The treatments were arranged in a randomized complete-block design replicated three times. Yield and net returns from Gliricidia-amended plots were greater than those from the FYM-amended plots. Soil-moisture status during crop period and bulk density, soil pH, organic carbon (C), and phosphorus (P) at the end of the three-year experiment were comparable between Gliricidia-and FYM-amended plots. Residual amounts of N and K were significantly higher in the plots amended with Gliricidia. Overall, the treatment receiving 50% recommended dose of fertilizers (RDF), Gliricidia at 2.5 t ha−1, and 2.5 kg ha−1 each of Azotobactor and phosphorus solubilizing bacteria (PSB) as soil inoculants (INM7) produced the highest grain yield (3.95 t ha−1), net returns (US

Effect of Biochar Amendment on Nitrate Leaching in Two Soil Types of India

400 ha−1), and highest benefit:cost ratio (2.39). Year x INM interaction effects for growth parameters, such as shoots plant−1, dry matter plant−1, dry root weight plant−1, and straw yield were significant. The INM7 was significantly better than most of the other INM treatments for growth parameters and straw yield during two (2003 and 2004) out of three study years and hence was consistently better. Therefore, integrated use of 50% RDF, 2.5 t ha− 1 Gliricidia, and 2.5 kg ha−1 each of Azotobactor and PSB (INM7) is recommended for improving productivity of finger millet in eastern India.

Runoff capture through vegetative barriers and planting methodologies to reduce erosion, and improve soil moisture, fertility and crop productivity in southern Orissa, India

Nitrate leaching from agricultural soils is a major concern to the groundwater, surface water bodies, and environment and also affects the farmers’ economy. The present study investigated the effect of native soil organic carbon and biochar amendment on the leaching of nitrate using a laboratory column study. The experiment was conducted taking two soil types of central India (Inceptisol and Vertisol differing in soil texture, viz. Loamy and clay texture). In each soil type, three native SOC levels (C 1: high SOC, C 2: medium, and C 3: low SOC) and four biochar amendment levels were taken in three replications in a factorial design. The four levels of biochar amendment were 0 (B 0), 5 (B 5), 10 (B 10), and 20 (B 20) g biochar kg−1 of air-dry soil. There was a significant effect of soil C (p < 0.01) and biochar (p < 0.01) amendment on the NO3 −-N leached, and the total dissolved salt (TDS) leached in both soil types. In the Inceptisol, NO3 −-N leaching increased with reduction in native SOC content, whereas the reverse trend was observed in the Vertisol. Biochar amendment reduced NO3 − leaching in both the soils, though the effect was higher in the Inceptisol. In both the soils, a significant effect of SOC level on leachate pH was observed with reducing pH with decrease in SOC level. As compared to control, the extent of reduction in the TDS leaching varied from 13 to 18% under biochar amendment in the Inceptisol and by about 5–6% in the Vertisol.