保护性耕作对陇中旱作农田水分特征的影响

陇中旱农区生产力水平低而不稳,而保护性耕作措施是农业可持续发展的重要途径.本研究依托2001年建立在陇中旱农区的长期不同耕作措施的定位试验,研究了不同耕作措施对土壤水分入渗、蒸发、作物产量和水分利用效率的影响.该试验共设6个处理,分别为传统耕作(T)、免耕秸秆覆盖(NTS)、免耕(NT)、传统耕作+秸秆翻入(TS)、传统耕作+覆膜(TP)、免耕覆膜(NTP),春小麦和豌豆年间轮作.结果表明:与T处理相比, NTS处理的小麦地和豌豆地的土壤容重显著降低,总孔隙度显著增加.保护性耕作措施降低了豌豆地0～5 cm土壤渗吸率,NTS处理渗吸率比T处理降低56.2%.保护性耕作提高了土壤饱和导水率,无论小麦地和豌豆地,NTS均比T处理显著提高了饱和导水率,增幅为52.8%～107.1%.保护性耕作显著降低了作物生育期棵间蒸发量,NTP、TP、NTS比T处理降低了14.4%～50.8%,并减弱了雨后土壤蒸发.保护性耕作提高了作物产量和水分利用效率,NTS、TP、NTP的产量比传统耕作提高了9.5%～62.8%,水分利用效率比传统耕作提高了0.4%～50.9%.因此,在陇中旱农区,保护性耕作措施可以提高水分利用效率,增加作物产量.

Effects of conservational tillage on water characteristics in dryland farm of central Gansu,Northwest China

Productivity is low and unstable in dryland farms of central Gansu, Northwest China. Conservational tillage is an important way for the sustainable development of agriculture. The effects of different tillage measures on soil moisture infiltration, evaporation, crop yield and water use efficiency (WUE) were investigated in this study based on a long-term experiment since 2001 in Longzhong. There were six treatments, i.e. conventional tillage with no straw (T), no-till with straw cover (NTS), no-till with no straw cover (NT), conventional tillage with straw incorporated (TS), conventional tillage with plastic mulch (TP), and no-till with plastic mulch (NTP), with annual rotation of spring wheat and pea. The results showed that compared with T, soil bulk density of NTS decreased and total porosity of soil increased significantly in wheat and pea land. Compared with conventional tillage, conservation tillage reduced soil infiltration rate in 0-5 cm in the pea field by 56.2%. Conservational tillage siginificantly increased soil saturated water conductivity in both wheat and pea lands. Compared with T, the saturated water conductivity in NTS was significantly increased by 52.8%-107.1%. Conservational tillage siginificantly reduced soil evaporation during growing season. Compared with T, the evapotranspiration of NTP, TP and NTS was significantly reduced by 14.4%-50.8%. The soil evaporation after rain was also decreased. Conservational tillage improved crop yield and water use efficiency by 9.5%-62.8% and 0.4%-50.9%, respectively. Therefore, conservational tillage could increase water use efficiency and crop yield in dryland farming area of central Gansu, Northwest China.