Effects Of Different Materials Combined With Chemical Fertilizer On Nitrogen Nutrient Of Saline Soil

The saline soil is affected by its own nature,resulting in low soil nitrogen nutrient utilization,which in turn causes the increase in the amount of chemical fertilizers and leads to the waste of nutrient resources and environmental pollution.Therefore,improving the nitrogen nutrient utilization and utilization efficiency in saline soil is a problem worthy of attention.This research takes saline soil and irrigated desert soil in Hexi area of Gansu as the research object,adding different materials(sulfur,biological fertilizer and other improved materials and cow manure,pig manure and other organic fertilizer),through pot experiment,cultivation experiment and field experiment in three ways,Studied the effects of different materials on the transformation and utilization of nitrogen nutrients in saline soil,and provided a scientific basis for optimizing fertilization,increasing efficiency and increasing production and improving fertility in the saline areas of northwestern China.The following main results and progress have been achieved.1.The effects of sulfur powder,biological bacterial fertilizer,commercial organic fertilizer and straw combined with chemical fertilizer on nitrogen change in saline soil were studied through cultivation experiment.The results showed that the combined application of sulfur powder and chemical fertilizer could increase the contents of alkali hydrolyzable nitrogen,microbial nitrogen and nitrate nitrogen,but had little effect on total nitrogen and ammonium nitrogen;Microbial fertilizer could increase soil total nitrogen,alkali hydrolyzable nitrogen,microbial nitrogen and nitrate nitrogen,but had little effect on ammonium nitrogen;Commercial organic fertilizer or straw could increase soil total nitrogen,alkali hydrolyzable nitrogen,microbial nitrogen,ammonium nitrogen and nitrate nitrogen,among which commercial organic fertilizer had the greatest effect on nitrogen nutrient.Compared with the control,the contents of total nitrogen,alkali hydrolyzable nitrogen,microbial biomass nitrogen,nitrate nitrogen and ammonium nitrogen in this treatment increased by 23.4%,24.9%,58.3%,19.9% and 348.9% respectively.The results showed that the combination of different improved materials and chemical fertilizer could further improve the soil nitrogen nutrient,and the improvement effect was sulfur +biological bacterial fertilizer < sulfur + commercial organic fertilizer,sulfur + straw <sulfur + biological bacterial fertilizer + commercial organic fertilizer + straw.The combination of sulfur powder,biological bacterial fertilizer,commercial organic fertilizer and straw with chemical fertilizer had the best effect Compared with the control,the contents of alkali hydrolyzable nitrogen,microbial biomass nitrogen,nitrate nitrogen and ammonium nitrogen increased by 25.9%,23.3%,149.6%,25.6% and 208.1%,respectively.2.The effect of different organic fertilizers combined with chemical fertilizers on nitrogen nutrients changes in saline soil was studied through pot experiments.It was found that the combined application of cow manure,sheep manure,chicken manure,pig manure,straw or commercial organic fertilizers and chemical fertilizers can increase the total nitrogen,alkaline nitrogen,microbial nitrogen,acid hydrolyzed nitrogen and other nitrogen indicators in the soil to varying degrees The content of commercial organic fertilizer,pig manure,chicken manure increased greatly.Among them,the total nitrogen,alkali-hydrolyzable nitrogen,and microbial nitrogen increased by 8.33%,11.23%,and23.53%,respectively.Hydrolyzed nitrogen,non-acid hydrolyzed nitrogen,and amino acid nitrogen increased by 7.17%,19.91%,and 9% respectively.Relatively speaking,straw has little effect on soil nitrogen nutrients.3.The pot experiment of wheat showed that the yield of wheat increased by 2.54%,5.57%,6.90%,8.30%,1.39% and 10.43% respectively compared with the control after applying cow manure,sheep manure,chicken manure,pig manure,straw or commercial organic fertilizer in combination with chemical fertilizer.As for the utilization rate of total nitrogen in the same season,the application rate of commercial organic fertilizer or pig manure combined with chemical fertilizer was 23.93% and 23.03% respectively,while that of other organic fertilizers combined with chemical fertilizer was lower than that of chemical fertilizer.Correlation analysis showed that under the condition of combined application of organic and inorganic fertilizer,alkali hydrolyzable nitrogen and microbial nitrogen were significantly or extremely significantly correlated with total nitrogen use efficiency,which were the main factors affecting nitrogen availability and nitrogen use efficiency.4.Through field experiments,the effects of different improved materials combined with chemical fertilizer on nutrient status and yield of saline soil were further studied.The results showed that on the basis of saline soil,20% reduction of chemical fertilizer(80%conventional fertilization)made soil total nitrogen,alkali hydrolyzable nitrogen,microbial biomass nitrogen and other nitrogen nutrients and wheat yield decreased in varying degrees compared with conventional fertilization(100%).The results showed that 80%conventional fertilization plus high-volume commercial organic fertilizer had better performance in improving nitrogen nutrient and soil organic matter in saline soil.The increase rates of soil total nitrogen,alkali hydrolyzable nitrogen,microbial biomass nitrogen,ammonium nitrogen and nitrate nitrogen were 16.1%,14.7%,48.2%,9.1% and100.8% respectively,and the soil organic matter was 28.9% higher than that of conventional fertilization;The results showed that 80% conventional fertilizer + high commercial organic fertilizer and 80% conventional fertilizer + high biological bacteria fertilizer had obvious effect on increasing yield,and the two treatments increased yield by19.3% and 19.0% respectively;In general,in the case of chemical fertilizer reduction,the combined application of commercial organic fertilizers and chemical fertilizers is the best choice to improve the soil nitrogen nutrient status in saline soil areas and maintain or increase crop yields.