本文選題：團(tuán)聚體組成和穩(wěn)定性　切入點：LB法　出處：《甘肅農(nóng)業(yè)大學(xué)》2015年碩士論文

【摘要】：為探明不同耕作措施對土壤團(tuán)聚體穩(wěn)定性以及團(tuán)聚體中有機(jī)碳、全氮、全磷的影響,借助干篩法、約得爾法和LB法分析團(tuán)聚體穩(wěn)定性,依托布設(shè)于隴中黃土高原雨養(yǎng)農(nóng)田豆-麥雙序列輪作系統(tǒng)的不同耕作措施長期定位試驗,共設(shè)4種耕作措施:傳統(tǒng)耕作(T)、免耕不覆蓋(NT)、傳統(tǒng)耕作+秸稈還田(TS)、免耕+秸稈覆蓋(NTS),旨在探索適合于該區(qū)農(nóng)業(yè)可持續(xù)發(fā)展、環(huán)境友好型、減緩水土流失且提高土壤固碳和養(yǎng)分的最佳耕作模式,主要結(jié)論如下:1.保護(hù)性耕作措施均可提升團(tuán)聚體含量和穩(wěn)定性,免耕+秸稈覆蓋處理效果最好。耕作措施對團(tuán)聚體組成的影響各不相同,但是較之傳統(tǒng)耕作措施,免耕、傳統(tǒng)耕作+秸稈還田和免耕+秸稈覆蓋均可不同程度提高≥0.25mm機(jī)械穩(wěn)定性和水穩(wěn)性團(tuán)聚體含量,也可提升機(jī)械穩(wěn)定性和水穩(wěn)性團(tuán)聚體平均重量直徑(MWD),降低團(tuán)聚體破碎率(PAD),綜合來看,NTS處理效果最優(yōu)。2.保護(hù)性耕作措施可提升團(tuán)聚體抗水蝕能力,免耕+秸稈覆蓋處理效果最好�？焖贊駶櫡�、慢速濕潤法和預(yù)濕潤后擾動法處理后,各土層中均以免耕+秸稈覆蓋措施水穩(wěn)性團(tuán)聚體MWD和≥0.25mm水穩(wěn)性團(tuán)聚體含量最高。因此,免耕+秸稈覆蓋處理對減緩由“氣爆”、“水爆”以及雨滴打擊而引起的團(tuán)聚體崩解的效果最好。3.保護(hù)性耕作各措施可提升團(tuán)聚體固碳、氮、磷的能力,其中免耕+秸稈覆蓋處理效果最好,同時微團(tuán)聚體固定有機(jī)碳、全氮和全磷的能力高于大團(tuán)聚體的。不同耕作措施下各粒級團(tuán)聚體中有機(jī)碳、全氮、全磷含量均以免耕+秸稈覆蓋處理最高,傳統(tǒng)耕作+秸稈還田處理次之。不同耕作措施0.25mm粒級微團(tuán)聚體中有機(jī)碳、全氮和全磷含量普遍高于其他粒級的。
[Abstract]:In order to investigate the effects of different tillage practices on the stability of soil aggregates and the organic carbon, total nitrogen and total phosphorus in the aggregates, the stability of the aggregates was analyzed by means of dry sieve method, Yorkshire method and LB method. The long-term localization experiment of different tillage measures based on the double sequence rotation system of soybean and wheat in the rain-fed farmland on the Loess Plateau in the middle of Gansu Province was carried out. There were four kinds of tillage measures: traditional tillage, no mulching, no mulching, no straw returning to field, no tillage straw mulching NTS, in order to explore suitable for the sustainable development of agriculture in this area, and environmental friendly type. The main conclusions are as follows: 1. Conservation tillage can improve aggregate content and stability. The effect of no-tillage straw mulching was the best. The effect of tillage on aggregate composition was different, but compared with traditional tillage, no-tillage was the best. The mechanical stability of 鈮，

本文編號：1667442