| The Loess Plateau in northwest China is a typical rain-fed agricultural area,and the shortage of soil moisture is the main limiting factor of the production and development of agriculture in this area.In addition,the traditional tillage has already maintained for many years that leading to a more shallow ploughing layer and a harder topsoil,which affects the soil and water conservation and sustainable development of agriculture negatively.In order to explore effective agricultural technical measures to improve the utilization efficiency of farmland soil water,a systematic experiment on ground mulching measures was carried out on the mountain terraces of Ansai County,northern Shaanxi province.The soil moisture,temperature,electrical conductivity,main plant traits,yield and water use efficiency(WUE)of crops were monitored and analyzed using 4 typical experimental treatments of plastic film mulching(ZM),straw mulching with amount of 5000 kg/hm~2(ZJ5),straw mulching with amount of 2500 kg/hm~2(ZJ2)and traditional tillage(ZC,control treatment).The main findings are as follows:Firstly,the soil moisture content of cropland can be increased by all mulching measures,and the water storage effect of plastic film mulching is better than that of straw mulching.During the growth period of crops,the average soil moisture content by volume of the 0-280 cm soil profile under ZM and ZJ5 treatments increased by30.08%-34.19%and 21.15%-23.24%,respectively.In the 0-60 cm soil profile with widely distributed roots,the water consumption of ZC during the growth period was higher than that of the ground covering measures,among which the water consumption of ZM was 0.82%-0.92%higher than that of ZJ5 treatment.Secondly,in each growth stage of crops,compared with the traditional tillage treatment,the plastic film mulching can increase the soil temperature of each profile of top 60 cm soil,and the straw mulching treatments have a both-sided effecting on the soil temperature,which have both a warming effect and a cooling effect.Thirdly,in each profile of top 60 cm soil,compared with traditional tillage treatment,plastic film mulching can improve soil electrical conductivity during the seedling stage of crops.The straw mulching treatment can improve the soil conductivity of each profile of top 40 cm soil at the seedling stage.Fourthly,the plant height,single leaf area,stem dry weight,total dry weight,hundred-grain weight and yield under ZM treatment were all higher than those under other treatments,and those crop properties under ZJ5 and ZJ2 treatment were also higher than those under ZC treatment.Compared with ZC,ZM can extremely significantly(p<0.01)increase the yield of crops by 23.80%-46.73%,ZJ5 can significantly(p<0.05)increase the yield of crops by 22.94%-34.61%,but the yield difference between ZM and ZJ5 was not significant.The WUE of ZM is extremely significantly(p<0.01)higher than that of ZC treatment 26.03%-47.50%,the WUE of ZJ5 is extremely significantly(p<0.01)higher than that of ZC treatment 26.30%-36.37%,but the WUE difference between ZM and ZJ5 has not reached a significant level.Finally,within a certain range,crops yield was positively correlated with the soil water storage,soil temperature and soil conductivity of 0-60 cm soil profile during the whole growth period.And compared with other growth stages,crops yield is closely related to soil water,heat and salt conditions at seedling stage,which showed that crop yield is extremely significantly positively correlated with soil water storage and soil electrical conductivity at seedling stage.In addition,the soil water storage and soil temperature at the seedling stage were positively correlated with the soil electrical conductivity at the seedling stage.The results show that the soil water content,crops yield and WUE of traditional tillage are the lowest,while the soil water consumption is the highest,which is not conducive to the sustainable development of dry farming.Both plastic film mulching and straw mulching can effectively retain soil moisture,promote crop yield and improve soil WUE.In addition,plastic film mulching has better economic benefit among the ground mulching measures,which can be applied to dry cropland in hilly and gully regions of the Loess Plateau.However,straw mulching can replace plastic film mulching to some extent in the case of scarce rainfall or plastic pollution not effectively solved,and the straw mulching amount of 5000 kg/hm~2 is more appropriate. |
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