How to reasonably determine the amount of nitrogen Fertilizer in accurate quantitative cultivation of Rice

The quantification of nitrogen needs to consider the law of fertilizer requirement of high-yield rice, the law of soil nitrogen supply, the characteristics of fertilizer and the utilization rate of fertilizer in the current season, as well as the changes of various conditions during the growth period, including total nitrogen quantity and nitrogen application method.

Determination of total nitrogen: the proportion of nitrogen, phosphorus and potassium obtained through soil testing formula and other tests should be regarded as the local reasonable proportion, and then according to the local application rate of high-yield nitrogen fertilizer, according to the reasonable proportion of nitrogen, phosphorus and potassium in the soil testing formula "3414" test, determine the specific amount of nitrogen, phosphorus and potassium for high-yield cultivation. The determination of total nitrogen application was calculated by Stanford difference method: total nitrogen application (kg / mu) = (target yield nitrogen requirement (kg)-soil nitrogen supply (kg)) / nitrogen fertilizer utilization rate (%) in the current season. The more the amount of total nitrogen, the lower the utilization rate of fertilizer, the different proportion of operation and research, and the different utilization efficiency of fertilizer. Generally speaking, under the premise of ensuring the local yield level unchanged or slightly increased, the use of accurate quantitative cultivation technology of rice can save 20% and 30% of fertilizer.

Application method of nitrogen fertilizer: the experiment and demonstration showed that heavy application of panicle fertilizer could promote panicle differentiation and increase the number of grains per spike, and the best ratio of basal tiller fertilizer to panicle fertilizer was 5:5 or 6:4. This fertilization method could achieve high yield and significantly improve fertilizer use efficiency.

Nitrogen application time: the period of nitrogen application mainly follows two principles: one is to ensure that there is no nitrogen deficiency in rice at the effective tillering stage, and to maintain a reasonable gradual decline of nitrogen concentration to the nitrogen deficiency level at the ineffective tillering stage. Second, the nitrogen level increased gradually at the beginning of panicle differentiation, reached the level of no nitrogen deficiency after secondary branch differentiation, and maintained to the milk stage, and decreased reasonably after milk ripening, which was beneficial to improve material transportation. tillering fertilizer was applied 7 days after transplanting, flower promotion fertilizer was applied at the beginning of young panicle differentiation, and flower protection fertilizer was applied at the growth of the penultimate leaf.