不同耕作措施对黄土高原旱地土壤呼吸的影响

在甘肃省定西市李家堡镇设置不同耕作措施试验，对春小麦、豌豆双序列轮作下的土壤呼吸及其对应时间的冠层温度、土壤水分进行了测定.结果表明：春小麦和豌豆在整个生育期内的土壤呼吸都表现出不同的变化趋势，春小麦地土壤呼吸在拔节前期、灌浆期和收后分别达到高峰期；豌豆地土壤呼吸在五叶期、吐丝期、开花结荚期和收后分别达到高峰期.免耕秸秆覆盖处理和传统耕作处理下春小麦地土壤呼吸日变化明显，免耕秸秆覆盖处理明显低于传统耕作处理；而豌豆地土壤呼吸日变化不明显.春小麦和豌豆冠层温度均与土壤呼吸呈显著线性相关，春小麦孕穗期相关性最高，灌浆期次之；豌豆开花结荚期相关性最高，分枝期次之.土壤含水量与土壤呼吸间存在极显著的凸型抛物线型相关,保护性耕作下的相关性都高于传统耕作，其中免耕秸秆覆盖处理的春小麦地和豌豆地土壤含水量与土壤呼吸的相关性在各层次土壤中均为最高，10～30 cm土壤含水量对春小麦地土壤呼吸的影响最大，5～10 cm土壤含水量对豌豆地土壤呼吸的影响最大.与传统耕作相比，免耕秸秆覆盖、免耕、传统耕作秸秆还田、传统耕作结合地膜覆盖、免耕结合地膜覆盖5种保护性耕作措施都能不同程度地降低土壤呼吸，其中免耕秸秆覆盖优势最明显.

Effects of different tillage measures on upland soil respiration in Loess Plateau

A field experiment was conducted in Lijiabu Town of Dingxi City.Gansu Provirice to study the soil respiration and its relations with the canopy temperature and soil moisture content in a rotation system with spring wheat and pea under effects of difierent tillage measures.Six treatments were installed,i.e.,tillage with no straw-or plastic mulch(conventional tillage,T).tillage with straw mulch(TS),tillage with plastic mulch(TP),no-tillage(NT),no-tillage with straw mulch(NTS),and no-tillage with plastic mulch(NTP).During the growth periods of spring wheat and pea,soil respiration had different change patterns,with the peaks appeared at the early jointing,grain-filling,and maturing stages of spring wheat,and at the 5-leaf,silking,flowering and poding,and maturing stages of pea.There was an obvious difference in the diurnal change of soil respiration in spring wheat field between treatments NTS and T,and the soil respiration rate was significantly lower in NTS than in T;while the soil respiration in pea field had less diurnal change.Soil respiration rate had a significant linear relationship with the canopy temperature of both spring wheat and pea,the correlation coefficient being the highest at booting stage of spring wheat and at flowering and poding stage of pea,followed by at grain-filling stage of spring wheat and at branching stage of pea.There was also a significant parabola relationship between soil respiration rate and soil moisture content,the correlation coefficient being higher under conservation tillage than under conventional tillage,with the highest under NTS.The moisture content in 10-30 am soil layer of spring wheat field and that in 5-10 cm soil layer of pea field had the greatest effects on soil respiration.Comparing with conventional tillage,all the five conservation tillage measures decreased soil respiration,with the best effects of no-tillage with straw mulch.