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Northwest University of Science and Technology (2005)

Soil Mineral Nitrogen and Its Effects on Crop Growth and Nutrient Use in Winter Wheat and Summer Maize Rotation on Dryland

Wang Xi Na

Titre  : Soil Mineral Nitrogen and Its Effects on Crop Growth and Nutrient Use in Winter Wheat and Summer Maize Rotation on Dryland

Auteur : Wang Xi Na

Grade : Master 2005

University : Northwest University of Science and Technology

Résumé
Nitrogen fertilizer is a major agricultural production and measures the right amount of nitrogen fertilizer to improve crop yields and maintain land productivity is of great significance. However, long-term unreasonable nitrogen fertilizer inputs result in a large number of mineral nitrogen residues in the soil. Nitrate mainly exist in the form of surplus nitrogen in dryland soil with water movement and migration, and can be converted into N2O losses caused by the potential threat of surface and groundwater and atmospheric. At the same time, the existence of a large surplus of nitrogen in the soil so the nitrogen use efficiency decreased yield little effect or even reduce production, has brought huge economic losses. In this study, in northern traditional winter wheat / summer maize rotation cultivation conditions, set different nitrogen levels, collecting soil and plant samples of winter wheat and summer maize growth period, the determination of soil mineral nitrogen and plant nutrients, to explore the semi-arid farmland ecosystems soil profile mineral nitrogen migration law and the validity of the crops, deep soil migration to optimize fertilization and cropping systems to reduce the residual nitrate nitrogen in soil and to provide a theoretical basis. The results showed that : 1, regardless of winter wheat, summer corn, preplant soil mineral nitrogen (Nmin) on crop yield and nitrogen fertilizer effects have a major impact. Higher soil Nmin can promote crop growth of winter wheat and summer maize nitrogen utilization were only about 39% and 5 to 22%, most of the fertilizer nitrogen to Nmin residue in the soil profile, or other forms of loss. View from winter wheat / summer maize rotation system of soil nitrogen balance, nitrogen fertilizers increase yield and utilization with increasing amount of nitrogen sharp decline in soil residual Nmin with nitrogen rate increase and a sharp increase in the apparent N losses show a downward trend in nitrogen rate increased to a certain height. , Planting and leisure affect the soil moisture content and the amount of nitrate accumulation, accumulated no significant effect of ammonium nitrogen. Planting corn due to uptake by plants, soil moisture and nitrate to the upward movement of the main crop consume a lot, not excessive accumulation in the soil can inhibit leaching. Leisure favor the accumulation of moisture in the soil profile lower, thus increasing the migration and accumulation of nitrate to the subsoil. Nitrogen rate impact 0-1m soil N accumulation of 1-2m soil N accumulation and 0-2m ammonium nitrogen accumulation in a lesser extent, does not affect soil nitrate and ammonium nitrogen with the growth of the dynamic trend. Early growth stage, nitrate is mainly distributed in the 0-60cm soil layer, gradually moving to lower soil with moisture infiltration, but moving slower than the water, ultimately failed to move to 1-1.2m, nitrate accumulation peak increased with increasing amount of nitrogen ; cumulative amount of ammonium nitrogen in the soil profile is very small, the effects of nitrogen application rate their profile distribution confined in the jointing stage, after which the ammonium nitrogen distribution in 0-2m profile uniform nitrogen rate and growth period. Nitrogen rate affect the growth of summer maize dry matter accumulation and nitrogen and phosphorus absorption and transfer. No nitrogen, the growth of summer maize dry matter synthesis and nutrient absorption hindered the harvest grain dry matter and nitrogen and phosphorus from the grain filling stage

Mots clés : Winter Wheat Summer Corn Soil Nitrate Ammonium nitrogen Nutrient transfer

Présentation (Dissertation topics)

Page publiée le 29 septembre 2014, mise à jour le 10 octobre 2017