| The inland river basin, Hexi corridor, is one of main food bases in Gansu Province, China. It is relatively one of fast developed region in economics in Gansu Province. However, many problems,such as social, ecological, environmental problems associated with fast economic development become more and more serious. For example, land desertification is aggravated; soil salinity areas are enlarged, water resources are over exploited etc. Currently the model of economic development is still premature with large consumption of resources. No-till or minimum-tillage with straw mulch techniques which have been developed overseas many years was tested for the sustainable development of agriculture in Hexi Corridor. No-till or minimum-tillage with straw mulch techniques can help to reduce the contradiction between water resources and social and economic development, alleviate the water resources pressure. It is one of the efficient water saving methods with low input. There were three treatments, no-till with straw mulch (NTS), conventional tillage with bare ground (CTB) and conventional tillage with straw incorporated (CTS). The objective of the experiment was to study effects of no-till technique on the water saving in summer and winter fallow period for the spring wheat crops. Soil temperature, irrigation efficiency, soil bulk density, crop growth, yield and social economic performance were measured. The results from the current research would increase the adoption of conservation tillage and supply technical support when the conservation tillage is implemented in Hexi corridor, Gasu Province. 1. Effects of water saving: NTS can conserve precipitation and reduced soil water evaporation on summer fallow. The storage water was 30.62mm and 23.91mm more than CTB and CTS, respectively. Also soil water mainly stored in 0~50cm soil. Soil water content was different depending on winter storage irrigation quota and tillage methods for the winter fallow. Under the same winter storage irrigation quota, soil water contents were significant different among NTS, CTB and CTS. However, no significant difference in soil water content was found among treatments for the same tillage. The interaction between tillage and winter storage irrigation quotas had no significant difference. The results showed that the irrigation quota can be reduced to 975~ 1350m3/hm2 or less with NTS compared with conventional storage irrigation. NTS changed the distribution of soil water in space and time during the spring wheat growth season. From sowing to seedling, the daily soil water consumption varied with different soil moisture contents. During early and late-season of spring wheat growing stage, NTS had the effects of reducing soil water consumption, whereas in the mid growing season, the soil water consumption increased due to vigorous crop growing. Overall, soil water consumption on NTS was similar to the other treatments during the whole growing period. 2. Effects of temperature regulation: NTS can increase soil temperature when air temperature is lowand reduce soil temperature when air temperature is high. It has obvious function of temperature regulation. The effects of temperature regulation were obvious at 8:00 AM when the air temperature was relatively low. The accumulated soil temperature (>0°C) on NTS was 14.0 and 18.8°C more than CTB and CTS on soil surface, respectively, but no difference in soil temperature in the 5~ 25cm soil. At 14:00 PM soil temperature was relative high in the soil surface but low in other soil layers for all treatments. The rate of soil temperature increase for NTS was slower than other two treatments. However, the accumulated temperature at soil surface was 522.7 and 477.2°C lower on NTS than CTB and CTS, respectively. At 19:00 PM while air temperature was low, the accumulated soil temperature at surface was higher on NTS than CTB and CTS, indicating that soil temperature on NTS kept increasing. The accumulated soil temperature on NTS decreased from 522.7 and 477.2°C at 14:00 PM to 108.6 and 80.4°C at 19:00 PM for CTB and CTS, respectively. Therefore, NTS had the effects of increasing soil temperature in the morning, decreasing soil temperature at noon, and prolonging and reducing the rate of soil temperature fall in the evening. During the whole growth period of spring wheat, NTS can regulate the soil temperature. NTS can increase soil temperature in the early stage when air temperature was low, but decrease soil temperature in the middle and later stage when air temperature was high. The effects of regulating soil temperature related on NTS was more obvious at the surface soil with rapid soil temperature changes at 5cm due to variation of soil bulk density. The effect of temperature regulation associated with NTS (increase soil temperature when air temperature is low and decrease soil temperature when air temperature is high) can be useful to seek for the best combination water and heat balance for the spring wheat growth. 3. Irrigation efficiency: The irrigation efficiency and quality on NTS were reduced by stubble retention. The irrigation efficiency showed difference between three tillage treatments under different irrigation time and flux. NTS had the effects of increasing soil bulk density and heat conductivity. 4. Effects of yield increase: There were no significant effects in yield between tillage methods and winter storage irrigation quotas when same irrigation quotas were used during spring wheat growth period. Overall, the spring wheat yield was the highest under NTS with winter storage irrigation quota of 1350 m3/hm2 (6681 kg/hm2), lowest under CTB with winter storage irrigation quota of 2100 m3/hm2 (5489 kg /hm2), while CTB with winter storage irrigation quota of 1725 m3/hm2 was in the middle (6674 kg /hm2). NTS can optimize spring wheat yield factors and reduce production costs.
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