水旱轮作体系下水—旱转换过程中土壤养分变化规律研究

发布时间：2018-04-17 17:46

本文选题：水旱轮作 + 干湿交替　；参考：《四川农业大学》2015年硕士论文

【摘要】：水旱轮作是-种能提高地力的可持续种植方式,对缓解人口增长造成的粮食需求压力有很大的作用。水-旱转换过程作为水旱轮作系统稻田环境变化最为强烈的过程之-,期间稻田水分条件的频繁变化,使土壤中的氧化还原状况快速转换,从而对土壤的养分循环变化产生很大影响。本文以水-旱转换过程中的土壤养分变化为主要研究对象,通过小区定位试验,设置了旱作、水旱、和水水3个处理。深入研究水旱轮作体系下水-旱转换过程对土壤养分的影响,阐明了在水-旱转换过程中,各处理的土壤养分时空变化特点和养分差异,分析了土壤环境因子与速效养分间的相关性。得到以下主要结果：(1)由于旱作和稻作水热条件的差异,水旱转换过程中稻作处理有机质、全氮和速效氮含量方面显著高于旱作,而土壤速效磷、速效钾含量方面则相反,直到下季作物整地播种前依然如此,因而在种植下季作物时应根据实际调整N、P、K肥的施用。(2)干湿交替期间,除土壤有机质、有效氮、速效钾外,可能是由于干湿交替强度相对不够的原因,未出现明显的周期性变化,其他土壤养分均相应表现出随灌水和落干的周期性变化；且在水稻收获后的落干期,水水处理淹水后,土壤pH和Eh值,有逐步恢复至稻田干湿交替期的趋势,有机质、全氮和有效氮含量增加,同时淹水提高了磷的溶解性,造成了钾离子的淋失。而水旱处理落干过程中,除速效钾和铵态氮同样降低外其他土壤养分变化与淹水处理基本相反。(3)对干湿交替前后各处理的土壤养分分析发现,干湿交替加强了土壤碳的矿化,并促进了有机氮向无机氮的转化,且使磷的溶解性降低,同时影响了土壤的固钾能力,但对土壤全氮和硝化作用影响却不显著,这可能与干湿交替的频率、强度以及持续时间有关。(4)对土壤养分与环境因子之间的相关性分析表明：水旱轮作土壤pH与速效氮、速效磷之间,呈显著正相关,而在速效钾方面却无显著相关性,这可能与稻作灌水环境钾离子的淋失有关,Eh值与土壤速效养分的相关性关系则与pH相反。可见稻田土壤环境因子的变化对土壤速效养分会产生很大的影响。
[Abstract]:Flood and drought rotation is a kind of sustainable planting method which can improve soil fertility. It has great effect on alleviating the pressure of food demand caused by population growth.The process of water-drought transformation is one of the most intense environmental changes in paddy field in the system of flood and drought cropping, during which the frequent changes of water conditions in paddy fields make the redox status in soil change rapidly.Therefore, it has great influence on the change of soil nutrient cycle.In this paper, the change of soil nutrients in the process of water-drought conversion was studied. Through the plot location experiment, three treatments were established: dry cropping, flood and drought, and water and water.The effects of water-drought conversion process on soil nutrients in flood and drought rotation systems were studied, and the temporal and spatial variation characteristics and nutrient differences of soil nutrients in the process of water-drought transformation were clarified.The correlation between soil environmental factors and available nutrients was analyzed.The main results are as follows: (1) because of the difference of water and heat conditions between dry cropping and rice, the contents of organic matter, total nitrogen and available nitrogen in rice treatment were significantly higher than those in dry cropping, but the contents of soil available phosphorus and available potassium were opposite.This is still the case until the next crop is planted on the ground, so when planting the next crop, we should adjust the application of Nu Pu K fertilizer according to the actual conditions, except for soil organic matter, available nitrogen and available potassium, during the alternate period of dry and wet.It is possible that there is no obvious periodic change of soil nutrients due to the relative insufficient intensity of dry and wet alternation, and other soil nutrients all show periodic changes with irrigation and drying, and at the dry stage after harvest of rice, the water treatment is after flooding, and the results are as follows: (1) during the dry period after harvest of rice, there is no obvious periodic change of soil nutrients.The pH and Eh values of soil gradually recovered to the alternate period of dry and wet rice fields. The contents of organic matter, total nitrogen and available nitrogen increased, and the solubility of phosphorus was improved by flooding, which resulted in the leaching of potassium ions.However, in the dry process of flood and drought treatment, except available potassium and ammonium nitrogen, the change of soil nutrients was similar to that of flooding treatment. The analysis of soil nutrients before and after dry and wet alternation showed that dry and wet alternation enhanced the mineralization of soil carbon.It also promoted the conversion of organic nitrogen to inorganic nitrogen, decreased the solubility of phosphorus, and affected the potassium fixation ability of soil, but had no significant effect on soil total nitrogen and nitrification, which may be the frequency of the alternation of dry and wet.The correlation analysis of soil nutrient and environmental factors showed that the correlation between soil pH and available nitrogen and available phosphorus was significantly positive, but there was no significant correlation in available potassium.This may be related to the leaching loss of potassium ions in rice irrigation environment. The correlation between Eh value and soil available nutrients is contrary to pH.Therefore, the change of soil environmental factors has a great influence on soil available nutrients.
【学位授予单位】：四川农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S158

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