Substitution Of Chemical Fertilizer Research Articles

The recent trend of agricultural nitrogen flow in Japan and improvement plans

Nitrogen (N) flows associated with agricultural practices and environmental N risk, which is an index of environmental impact, in Japan from 1980 to 1997 were estimated, and the effect of improvement plans for reducing environmental N risk was simulated for two important prefectures. Recent trends have shown that the input of chemical fertilizer and manure is lower compared to crop production, which is also lower. Environmental N risk peaked in 1985 then became lower, and its content changed. Residual N on farmland, defined as N inputs onto farmland (chemical fertilizer, etc.) minus N outputs from farmland (crop uptake, etc.), peaked in 1985, then decreased, although non-utilized livestock excreta increased during the period. To simulate reduction of the environmental N risk, two prefectures that had high applications of chemical fertilizer and high livestock excreta production were selected. Simulated improvement plans were based on the results of past studies, such as low inputs of chemical fertilizer in crop production, substitution of chemical fertilizer by livestock excreta and/or active use of livestock excreta in forage production. Incorporation of these methods was successful in reducing environmental risk in those prefectures, although prefectures that had a large amount of livestock excreta could not find any effective improvement plan, due to lack of appropriate local land use.

Quantitative evaluation of environmental risk associated with nitrogen flow in agricultural production and mitigation plan for 2 typical prefectures in Japan

Nitrogen (N) flow and environmental risk in Japanese agricultural production were estimated for each prefecture in 1997 using a modified nutrient balance calculation system. N flows associated with agricultural production varied widely among the prefectures. The amount of excess N that remained on farmland (residual N), which is a source of environmental risk, also varied widely and was strongly affected by the level of inputs of chemical fertilizer and manure. The prefectures were grouped into 3 categories in relation to environmental risk. 1) Prefectures which had a lower environmental risk than the Japanese average. 2) Prefectures which had a higher environmental risk than the average due to high application of chemical fertilizer, and 3) due to the high production of livestock excreta. Two typical prefectures were selected to implement mitigation plans. Prefecture A belonged to category 2) and had the highest chemical fertilizer input in Japan. Therefore, it was considered that by decreasing the input of chemical fertilizer could be effectively reduced environmental risk. The mitigation plan was drafted to reduce the environmental risk to 69% of the present level. Prefecture B belonged to category 3), and was characterized by a high livestock excreta production of which 47% was not used as manure in the prefecture. By substitution of chemical fertilizer with manure for forage crops and more effective use of manure in paddy fields, it was estimated that the environmental risk in Prefecture B could be reduced to 77% of the present level.

Rice-wheat cropping system: assessment of sustainability under green manuring and chemical fertilizer inputs

Rice-wheat rotations are the most important cropping system of the Indo-Gangetic plains. We measured the long-term sustainability of the system for green manuring and chemical fertilizer input practices utilising the trends in grain yield, partial factor productivity (PFP), agronomic efficiency, benefit : cost ratio, soil organic carbon content (OC) and sustainable yield index (SYI). The data of a long-term experiment conducted at six locations in the Indo-Gangetic plain region of India revealed that grain yield and PFP of both rice and wheat declined under control (no fertilizer, no green manure) and sub-optimal fertilizer inputs (50 or 75% recommended fertilizer NPK) at all locations. Complete dose of fertilizer NPK (100% recommended) increased grain yields as well as PFP in rice but did not prevent decline in these parameters in wheat. Partial substitution of chemical fertilizer with Sesbania green manure, however, brought further improvement in yield and PFP in rice and the residual effect of green manure reversed the declining trend in wheat. The SYI and agronomic efficiency of fertilizers were also greater in plots receiving 100% fertilizer NPK or green manuring along with 50 or 75% recommended NPK. Benefit : cost ratio of fertilizer inputs and green manuring practices increased in both crops and for all treatments, indicating that the benefit accruing from fertilizer improved with time. At locations with high initial OC, a depletion of OC was noticed whereas OC increased at locations with low initial OC, with OC stabilizing between 0.60 and 0.65%. Trends in grain yield, PFP and agronomic efficiency of fertilizer appear promising tools to measure sustainability of fertilizer management practices.

Nitrogen uptake response of crops to organic nitrogen

Abstract Sustainability of agriculture became a major issue of global concern during this decade. Agronomic practices aimed at reducing the dependence on inputs such as chemical fertilizers can contribute to sustainability. Nitrogen (N) is the most limiting and commonly applied nutrient for crop production. The development of nutrient-responsive cultivars especially during the past three decades led to an intensive use of N fertilizers in many agricultural systems. Environmental and economic issues associated with such practices have, however, generated an interest in alternative management systems. These include practices such as exploitation of beneficial biological functions (symbiotic nitrogen fixation, etc.) and substitution of chemical fertilizers with farm-generated products.

Essential tremor: response to primidone.

<h3>ABSTRACT</h3> Soil microbial community and enzyme activities together affect various ecosystem functions of soils. Fertilization, as important agricultural management practices, are known to modify soil microbial characteristics; however, inconsistent results have been reported. The aim of this research therefore was to make a comparative study of the effects of different fertilization patterns (No N inputs (No N), 100% chemical fertilizer-N (CN) inputs (4/4CN) and different substitution rates of CN by organic manure-N (MN) (3/4CN+1/4MN, 2/4CN+2/4MN and 1/4CN+3/4MN)) on soil physicochemical properties, enzyme activities and microbial attributes in a GVP of Tianjin, China. Manure substitution of chemical fertilizer, especially at higher substitution rate (2/4CN+2/4MN and 1/4CN+3/4MN), improved soil physicochemical properties (higher soil organic C (SOC) and nutrient contents; lower bulk densities), promoted microbial growth (higher total phospholipid fatty acids and microbial biomass C contents) and activity (higher soil hydrolase activities). Manure addition caused a remarkable increase of the fungi/bacteria ratio and a distinct shift in the fungal (bacterial) community to greater abundance of arbuscular mycorrhizal fungi (G+ bacteria) compared with saprotrophic fungi (G− bacteria). These changes drove shifts toward fungal-dominated soil microbial communities and then optimized microbial community structure. Also, manure application increased soil biodiversity (microbial community and enzyme function), indicated by increased Shannon–Wiener diversity. Redundancy analysis indicated that the most possible mechanism of the impacts of different fertilization patterns on soil microbial characteristics may be the mediation of SOC and nutrient (N) availability (especially SOC) in this GVP of China. In conclusion, manure substitution of chemical fertilizer, especially at higher substitution rate, was more efficient for improving soil quality and biological functions.