Research On The Effects Of Subsurface Drip Irrigation In Cotton

【Objective】The lack of water resources is the main limiting factors of agricultural productionin arid region. Developing water-saving irrigation technology and improve the utilizationefficiency of irrigation water resources is an important way to alleviate the shortage of waterresources. Subsurface drip irrigation can reduce the evaporation loss of soil moisture, improvingland ecological environment, and simplifying the farming operation, has remarkablewater-saving and yield increasing effect. The objective of this study is (1) to study on soil watermovement and cotton water consumption under subsurface drip irrigation;(2) to clarify the effectof subsurface drip irrigation on the growth and yield of cotton;(3) to demonstrate the applicationof subsurface drip irrigation technology in cotton field. This study can promote the application ofsubsurface drip irrigation in cotton production in Xinjiang.【Method】The suitable drip line for subsurface drip irrigation and laying distance werescreened with a field simulation experiment. Five types of drip line were Yirun, Netafim-thin,Netafim-thick wall, Naan and local production. The laying distance of drip line was set as100,120,140and160cm, respectively. The effect of subsurface drip irrigation on dynamic of soilwater and cotton growth was studied with a check experiment. Effects of different irrigationamount on water consumption and cotton yield under subsurface drip irrigation were alsoinvestigated by a field experiment. Four irrigation amount treatments were270,405,465and525mm (representing low, moderate, and high water treatment, respectively). Differences ofcotton yield and economic benefit between surface drip irrigation and subsurface drip irrigationwere evaluated through multi-site demonstration test from2011to2013.【Results】(1) The head pressure loss of Netafim-thin, Netafim-thick wall, and Yirun drip lines weresmaller, and suitable for subsurface drip irrigation. But drip line of Naan and local productionshould not be used in subsurface drip irrigation.(2) Dry soil was observed in the surface0-10cm and below80cm depth when the layingspacing of drip line was100cm and120cm. When laying spacing was140cm, dry soil wasobserved in the surface0-20cm and below60cm depth. When laying spacing was160cm, drysoil was observed in the horizontal direction between the two lateral0-30cm wide.(3) Soil volumetric water content in the0-100cm soil profile maintained stable undersubsurface drip irrigation, and the range of average water content was21%~27%. Soil moistureat the surface10-20cm was relative low, which can effectively reduce the evaporation loss, andreduce the disease occurrence and boll shedding. The highest water content was observed in the30-40cm and80cm soil depth. Moreover, water content in the deeper soil layer (100-180cm) insubsurface drip irrigation was higher than that in surface drip irrigation, which could promote root penetration, enhance water and nutrient absorption, and increase the drought resistanceability.(4) Compared with surface drip irrigation, cotton growth period of subsurface drip irrigationwas4days in advance, leaf number increased6per plant, leaf area increased296.6cm2per plant,boll number increased0.6per plant; but the plant height and node number was lower than that insurface drip irrigation. No significant difference was found between subsurface drip irrigationand surface drip irrigation for total dry matter weight of cotton. The root dry weight ofsubsurface drip irrigation was14.8%higher than that of surface drip irrigation, and root/shootratio increased significantly.(5) Under subsurface drip irrigation, the maximum water consumption intensity was in20-30cm soil layer during cotton bud stage, and was in40-50cm soil layer after cotton blossomperiod. Boll development stage was the peak period of water consumption of cotton. Theirrigation quota was400-470mm during cotton growing period under subsurface drip irrigation.At the bud stage, the irrigation interval was7-8d and25-30mm for each irrigation quota. At theflowering stage and boll development stage, the irrigation interval was4-8d and40-50mm foreach irrigation quota.(6) Three years (2011-2013) demonstration results showed that cotton yield in subsurfacedrip irrigation was5.84%higher than that in surface drip irrigation, which represented lintincreasing by9.1kg/667m2, and saving the cost of191.6Yuan/667m2.