Studies on Maize-Legume Intercropping and their Residual Effects on Soil Fertility Status and Succeeding Crop in Upland Situation

To examine the advantages of cereal-legume intercropping system with maize as main crops, field studies conducted for two years on sandy upland loamy soils in Bihar plateau, India, indicated maize-groundnut as the best system. Yield advantages were noticed between 22–44 % over sole maize cropping. Different production indices largely indicated the same pattern in ranking intercropping treatments. Of the other legumes used, mung also showed potential whereas cowpea and soyabean did not. Increasing cropping intensities through use of interspace by legume did not significantly reduce maize yield, particularly in combination with groundnut and mung. Soil nitrogen enrichment through legume cultivation could be noted through examination of soil test values and yield of succeeding wheat crop. Wheat, however, did not show its promise as a follow-up crop without input of water and fertilizer.     

Identification of irradiated cashew nut by electron paramagnetic resonance spectroscopy

Cashew nut samples were irradiated at gamma-radiation doses of 0.25, 0.5, 0.75, and 1 kGy, the permissible dose range for insect disinfestation of food commodities. A weak and short-lived triplet (g = 2.004 and hfcc = 30 G) along with an anisotropic signal (g perpendicular = 2.0069 and g parallel = 2.000) were produced immediately after irradiation. These signals were assigned to that of cellulose and CO 2 (-) radicals. However, the irradiated samples showed a dose-dependent increase of the central line (g = 2.0045 +/- 0.0002). The nature of the free radicals formed during conventional processing such as thermal treatment was investigated and showed an increase in intensity of the central line (g = 2.0045) similar to that of irradiation. Characteristics of the free radicals were studied by their relaxation and thermal behaviors. The present work explores the possibility to identify irradiated cashew nuts from nonirradiated ones by the thermal behaviors of the radicals beyond the period, when the characteristic electron paramagnetic resonance spectral lines of the cellulose free radicals have essentially disappeared. In addition, this study for the first time reports that relaxation behavior of the radicals could be a useful tool to distinguish between roasted and irradiated cashew nuts.     

Hydrochemistry of Arsenic-Enriched Aquifer from Rural West Bengal, India: A Study of the Arsenic Exposure and Mitigation Option

The present study aims to understand the hydrochemistry vis-à-vis As-exposure from drinking groundwater in rural Bengal. The characteristic feature of the groundwaters are low Eh (range, ?151 to ?37 mV; mean, ?68 mV) and nitrate (range, 0.01–1.7 mg/l; mean, 0.14 mg/l) followed by high alkalinity (range, 100–630 mg/l; mean, 301 mg/l), Fe (range, 0.99–38 mg/l; mean, 8.1 mg/l), phosphate (range, 0.01–15 mg/l; mean, 0.54 mg/l), hardness (range, 46–600 mg/l; mean, 245 mg/l) and sulphate (range, 0.19–88 mg/l; mean, 7.2 mg/l), indicating reducing nature of the aquifer. The land use pattern (sanitation, surface water bodies, sanitation coupled with surface water bodies and agricultural lands) demonstrates local enrichment factor for As/Fe in groundwater. Among these, sanitation is the most prevailing where groundwater is generally enriched with As (mean, 269 μg/l) and Fe (mean, 9.8 mg/l). Questionnaire survey highlights that ～70% of the villagers in the study area do not have proper sanitation. This demonstrating the local unsewered sanitation (organic waste, anthropogenic in origin) could also cause As toxicity in rural Bengal. In the agricultural lands, higher mean values of alkalinity, phosphate, sulphate, hardness and electrical conductivity was observed, and could be linked with the excessive use of fertilizers for agricultural production. Bio-markers study indicates that the accumulation of As in hair and nail is related with the construction of exposure scenario with time dimension. The strength and weakness of the on-going West Bengal and Bangladesh drinking water supply scenario and achievability towards alternative options are also evaluated.     

Estimation of nitrogen and sulfur mineralization in soils amended with crop residues contributing to nitrogen and sulfur nutrition of crops in the North Central U.S

Predicting nitrogen (N) and sulfur (S) mineralization of crop residues from the preceding crop might be a useful tool for forecasting soil N and S availability. Two soils from eastern North Dakota and three crop residues – corn, spring wheat, and soybean were used in an 8-week incubation study to estimate N and S mineralization from crop residues. The cumulative N and S mineralized were fit to a first-order kinetic model. Cumulative N mineralized ranged between 0.34 and 2.15 mg kg^?1 and 0.45 to 3.41 mg kg^?1 for the Glyndon and Fargo soils, respectively. Un-amended soils showed higher N mineralization than residue treated soils. For S, the highest mineralization occurred in un-amended Glyndon soil and in spring wheat-amended Fargo soil. This study indicates that crop residue additions can have a negative impact on plant available nutrients due to immobilization of N and S during the time when crops need the nutrients most.     

Temperature response of ammonia and greenhouse gas emission from manure amended silty clay soil

Soil temperature plays an important role in organic matter decomposition, thus likely to affect ammonia and gaseous emission from land application of manure. An incubation experiment was conducted to quantify ammonia and greenhouse gas (GHG) (N₂O, CO₂ and CH₄) emissions from manure and urea applied at 215?kg N ha^?1 to Fargo-Ryan silty clay soil. Soil (250?g) amended with solid beef manure (SM), straw-bedded solid beef manure (BM), urea only (UO), and control (CT) were incubated at 5, 10, 15, and 25 °C for 31 days at constant 60% water holding capacity (WHC). The cumulative GHGs and NH₃ emission generally increased with temperature and highest emission observed at 25 °C. Across temperature levels, 0.11–1.3% and 0.1–0.7% of the total N was lost as N₂O and NH₃, respectively. Cumulative CO₂ emission from manure was higher than UO and CT at all temperatures (P?<?0.05). Methane accounted for <0.1% of the total C (CO₂?+?CH₄) emission across temperatures. The Q₁₀ values (temperature sensitivity coefficient) derived from Arrhenius and exponential models ranged 1.5–3.7 for N₂O, 1.4–6.4 for CO₂, 1.6–5.8 for CH₄, and 1.4–5.0 for NH_3. Our results demonstrated that temperature significantly influences NH₃ and GHG emissions irrespective of soil amendment but the magnitude of emission varied with soil nutrient availability and substrate quality. Overall, the highest temperature resulted in the highest emission of NH₃ and GHGs.     

Path Analysis of Important Growth Functions of Indian Mustard (Brassica juncea L. Czern and Coss)

Field experiment conducted at the Viswavidyalaya Farm during the winter seasons of 1980—81 to 1983—84 to study the effects of major six productive functions viz. number of inflorescence bearing primary branches, number of inflorescence bearing secondary branches, leaf area indices at flowering, number of seeds/siliqua, number of siliqua/m² and test weight of grains on the grain yields of eight elite varieties of Indian mustard ( Brassica juncea L. Czern and Coss) when sown on three different times revealed that correlations between them were close and positive in all the varieties. Path analysis of the data, further, showed that except the inflorescence bearing primary branches and the seeds/siliqua all other attributes showed high direct influences on grain yield; the maximum direct influence was obtained from number of siliqua/m².