Optimal Allocation Of Different Tillage Practices In Gently Sloping Farmland Of Loess Hilly Region

As the rapid development of economy and urbanization, in recent years，rural labor forcein Loess Plateau, especially in villages near the towns, have transferred from countryside tourban area, which led to the lack of rural labor force in countryside. To cut cost and time,most of the gently sloping land beside the villages was reserved and cultivated, which hasbeen an important source of soil and water loss under the new situation, while the terracesand farmland away from the village were abandoned. Most of the gently sloping lands by thevillages are distributed, out-of-shape and in small size, which are difficult to manage. Practicehas proven that adopting soil and water conservation tillage practice is an effective way tocontrol the soil erosion of gently sloping farmland in loess hilly region. After long-termpractice, the local residents have put forward some tillage practices which are adapted to thelocal natural environment conditions and superior in soil and water conservation. However,thought most of the tillage practices have been put into used, there is little research about it.The existing research by far merely focused on the tillage practices and ignored the effect ofcrop on runoff and sediment yield of tillage practices during the the rainy season. Most of therainfall mainly concentrated from June to September on Loess plateau, during which Maize,the main food crop in loess plateau, are planted. As the existing research showed, there wasless runoff and sediment yield on sloping farmland after being planted.As is discussed above, in this paper, the soil and water conservation benefit andrainwater resource utilization rate of different tillage practices （plant buffer strip, fish-scalepit, contour tillage, level trench planting, no-till farming, straw mulching）were studied ongently sloping farmland when planting Maize by the method of rainfall simulator experimentand runoff plots observation experiment. The results showed that：（1）The observation data of runoff plots showed: plant buffer strip, level trenchplanting, plant buffer strip-level trench planting and fish-scale pit could effectively hadstrong runoff-sediment regulation function and high rainwater resource utilization rate whichcould reach100percent; Compared to straight tillage, contour tillage did not haveoutstanding runoff-sediment regulation function and rainwater resource utilization rate.（2） The rainfall simulator experiment showed: With the increase of rainfall intensity,all the treatments’ function of runoff and sediment regulation weakened; with the growth of maize, all the treatments’ function of runoff and sediment regulation was enhanced, andsediment could be more effectively controlled than runoff; with the growth of maize, thefunction of runoff and sediment regulation of fish scale pit increased.（3）The observation data of runoff plots showed: After mulching straw, there was lesssediment yield under straight tillage and contour tillage; straw mulching had strongersediment regulation function than runoff regulation function; as for straight tillage, mulchingstraw reduced runoff while increasing the sediment yield.（4）The rainfall simulator experiment showed: Compared to ploughing, no-till farmingcould decrease the runoff and sediment yield to some extent; after mulching straw, ploughingcould effectively reduce the runoff and sediment, while no-till farming could reduce runoffwhile increasing the sediment yield.（5）The soil and water conservation mechanism of maize was studied by the method ofrainfall simulator experiment and the results showed: with the growth of maize, runoff andsediment regulation function of maize increased and sediment could be more effectivelycontrolled than runoff; under the rainfall intensity of60,90mm/h, sediment yield and leafarea index presented a significant negative liner correlation, while runoff amount and leafarea index presented an insignificant correlation.（6）Based on the research result in this paper and previous research conclusion, weproposed to adopt plant buffer strip and level trench planting to plant Maize in gently slopingfarmland in loess hilly region.