Research About Method Of Regulating Water And Sediment Of Terraced Greenhouse In Hilly Area Of The Loess Plateau

Reforestation projects were fully implemented during1997-2002in hilly area of LoessPlateau. The projects have caused arable land per capita decreased significantly, and it’srequired to increase yield per unit area, insure food security and develop efficient agriculture.As a typical pattern of efficient agriculture, terraced greenhouse has been popularized in hillyarea of Loess Plateau. Otherwise, terraced greenhouse has changed runoff and convergenceconditions of underlying surface, and caused serious erosion of terraced greenhouse duringrainstorm. As a result, research of water-sediment control mode is urgent needed fordeveloping efficient agriculture. This study investigated water-sediment control mode ofterraced greenhouse through location monitoring (Ansai, Majigou, Longquansi) and indoorsimulating experiments of artificial rainfall, and the main conclusions are followed:1.Terraced greenhouse has changed conditions of underlying surface, and then erosionregulation of terrace has changed. According to observation of terraced greenhouse erosionduring100-year rainstorm (2013) in Yan’an, and the results showed that: under conditionwithout protection, erosion of terraced greenhouse is serious---average depth of erosiongully is40%of ridge and the maximum depth s100%of ridge. However, if there is simplenatural drainage on the outer edge of greenhouse or using ridge-like farming, the erosionreduction is more than57%. Runoff intercepted by greenhouse is the main force of terraceerosion, and relationship of terrace erosion and intercepted runoff is logarithmic. The keyissue of regulating water-sediment of terrace is controlling runoff collected by greenhouse.2.Efficient use of soil and water resources on space outside the greenhouse is animportant pattern of regulating water and sediment for terraced greenhouse. Through indoorsimulating experiments of artificial rainfall, the study investigated runoff, runoff time anderosion changing regulation in bare slope, grass and straw mulch. The results showed that:grass and straw mulch can reduce surface runoff efficiently, promote runoff infiltration andprevent soil and water erosion; when grass coverage is about70%and rainfall density is lessthan45mm/h, the rainfall can be impounded totally and the average reduction of water is55%;when coverage of straw mulch is about90%, rainfall density is less than75mm/h---thereduction of water is100%, rainfall density is90mm/h and105mm/h---the reduction ofwater is50%, and the average reduction of water is80.7%. As a result, grass and straw mulch are proper method for regulating water and sediment outside terraced greenhouse.3.Pattern of regulating water and sediment for terraced greenhouse is cellar storage ofrunoff.Channels on base of greenhouse make the intercepted runoff import to storage facility,use vegetation filtration system to filter surface runoff and irrigate plant by mini-storagefacilities and drip irrigation technology.Size of rectangular channels on base of greenhouse is:width-0.2m, depth-0.1m; corrosion measurements is ridge-like farming using panicumvirgatum and waste straws to cover and import surface runoff to channels. Cellar selectsrubber cellar and MBER solidified soil cellar, and capacity is22.5m3(10m×1.5m×1.5m＝22.5m3). Mode of regulating water and sediment for terraced greenhouse can impound allrunoff, prevent terrace erosion and get clean water. A terraced greenhouse can save about1334yuan per year.