A quantitative determination method for the nitrogen destination of crop straws returned to the field

Abstract

The invention relates to a field returning crop straw nitrogen fate quantitative measurement method and belongs to the farmland nutrient cycling technology field. The method comprises steps that a first experiment plot and a second experiment plot isolated from external soil are preset, crops are grown on the first experiment plot, highly abundant 15N-labeled nitrogen fertilizer is applied at a crop growth period, the crops absorb the nitrogen fertilizer, straw marking is carried out after harvest, the marked straw is moved to the second experiment plot for field returning, later crops are then grown, 15N contents left in the marked straw, absorbed by the later crops and contained in the soil are measured at a critical growth period and after harvest, and dynamic field returning crop straw nitrogen conditions and fate thereof can be quantitatively monitored. The method is advantaged in that a measurement result can relatively visually reflect the nitrogen fate, the method is stable and reliable, external factor interference can be avoided, and technical supports are provided for understanding and researching field returning crop straw nitrogen release, mineralization characteristics and crop utilization characteristics.

Description

technical field [0001] The invention belongs to the technical field of farmland nutrient cycle, and in particular relates to a method for quantitatively determining the whereabouts of nitrogen in crop straws returned to the field. Background technique [0002] A large amount of crop straw is produced every year in the agricultural production system. In recent years, the annual output of major crop straw in China has exceeded 700 million tons. Straw returning to the field is one of the most effective ways to deal with crop straw. On the one hand, straw returning can significantly increase soil organic matter, improve soil porosity, agglomeration, adsorption, buffering and other physical and chemical properties, improve soil water storage and fertilizer retention capacity, and ultimately improve cultivated land quality and soil productivity; on the other hand, straw returning can also Return the mineral nutrients contained in the straw to the soil, compensate for the absorptio...

AI Technical Summary

Problems solved by technology

Many studies at home and abroad have made a lot of reports on the degradation law of returning straw itself, but there is still no clear understanding of the nitrogen release, mineralization characteristics and crop utilization characteristics in returning straw. In the study of the whereabouts of nitrogen, the nylon mesh bag method is generally used, that is, a specific amount of straw is put into the nylon mesh bag and buried directly in the soil at a certain depth, and taken out after a certain period of time to measure the degree of straw decomposition. First, this method The straw in the middle is concentrated together, and the actual contact area with the soil is small, thereby reducing the chance of soil microorganisms contacting the straw, thereby affecting its decomposition. Secondly, the existence of the nylon mesh bag is bound to affect the growth of the crop root system, thereby affecting the crop's ability to absorb the straw. Absorption of released nitrogen. In short, because the environment of returning straw under the nylon mesh bag method is inconsistent with the actual environment of returning straw, it cannot truly and objectively reflect the mineralization release law of straw nitrogen and crop utilization characteristics. , the previous studies often only focused on the degradation law of the straw itself, and the quantitative research on how the organic nitrogen of the straw is mineralized, the components of the inorganic nitrogen of the straw and how it is released to the soil, and the various destinations of the straw nitrogen returned to the field is still in a blank stage.