Study of nitrogen release pattern from organic manures is very essential to ensure nitrogen supply in adequate quantity and at proper time to crop plants in an acid soil. A laboratory incubation experiment was conducted to determine the nitrogen release pattern from vermicompost (V.C), poultry manure (P.M), neem, inorganic fertilizer (I.O) and its combinations applied to an acid soil at two different rates. Cumulative nitrogen mineralization was significantly higher throughout the incubation period for I.O, V.C+P.M and I.O+V.C while it was two weeks after incubation for V.C and V.C+Neem due to the inhibitory effect of neem on nitrification. The results indicated a significant increase in the rate of N mineralization in the first one week in which the highest rate of 3.36 mg N day -1 was observed for inorganic fertilizer and thereafter it slowed down. V.C followed by V.C+Neem recorded higher rate of N mineralization of 0.24 and 0.23 mg day -1 respectively, from 48 th days after incubation. V.C+Neem at 120 kg N equivalent ha -1 recorded the highest ammonia content of 42.1% to total available N while V.C+P.M recorded higher nitrate content of 82.3% at the end of the incubation period. Positive correlation between initial nitrogen and total mineralized N from the manures and fertilizers (R 2 = 0.563) was observed. Furthermore, addition of organic manures resulted in increase in soil pH where as inorganic fertilizer showed a slight decrease (5.73) than control (5.78).

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Pesticides are shown to have a great effect on soil organisms, but the effect varies with pesticide group and concentration, and is modified by soil organic carbon content and soil texture. In the humid tropical islands of Andaman, India, no systematic study was carried out on pesticide residues in soils of different land uses. The present study used the modified QuEChERS method for multiresidue extraction from soils and detection with a gas chromatograph. DDT and its various metabolites, α-endosulfan, β-endosulfan, endosulfan sulfate, aldrin, and fenvalerate, were detected from the study area. Among the different pesticide groups detected, endosulfan and DDT accounted for 41.7 % each followed by aldrin (16.7 %) and synthetic pyrethroid (8.3 %). A significantly higher concentration of pesticide residues was detected in rice-vegetable grown in the valley followed by rice-fallow and vegetable-fallow in the coastal plains. Soil microbial biomass carbon is negatively correlated with the total pesticide residues in soils, and it varied from 181.2 to 350.6 mg kg(-1). Pesticide residues have adversely affected the soil microbial populations, more significantly the bacterial population. The Azotobacter population has decreased to the extent of 51.8 % while actinomycetes were the least affected though accounted for 32 % when compared to the soils with no residue.

More than 10,000 years ago, humans began an experiment on the environmental consequences of resource use. The environmental changes were at first local. By 6000 years ago, the consequences had begun to be manifested at the regional and global scales. At the beginning of the experiment, Asia played a founding role. Populations were centered there, and agriculture and associated land-use change began there. Now Asia, with 60% of the world's population, is rapidly growing in terms of both population and economic development. Over the next few decades, population growth will slow, but economic growth will continue, resulting in large-scale losses of S, C, and N compounds to the atmosphere. A global challenge is to implement growth scenarios that, on one hand, will not limit the ability of the Asian population to attain a higher standard of living, but, on the other hand, will not result in a continued degradation of the environments within Asia as well as downwind and downstream of Asia.