Water And Fertilizer Use Efficiencies Of Potato Under Different Irrigation Patterns And Nitrogen Recommendation Of Under-Mulch-Drip Irrigated Potato

The north foot of Yinshan Mountain of Inner Mongolia is the advantage potatoproduction region of China, however, flood irrigation and overused nitrogen used for along time lead to serious problems such as resource waste and environmental pollution.In order to solve this problem, a variety of water-saving equipments were introdueced forpotato production in the area during last ten years, among which under-mulch-dripirrigation （UMDI） is applied and popularized gradually as a new type of potato irrigationmode. However, the comprehensive nutrient management technology of potatoproduction matching UMDI still needs to be further studied. In such background, theeffects of different irrigation methods were investigated consist of production efficiency,commodity characters, economical and the eco-environmental benefits of potatocultivation in this study. The field experiments were conducted in2009-2010in Wuchuan,a region located at the north foot of Yinshan Mountain in Inner Mongolia, the irrigationpatterns includes flood irrigation （FI）, ground sprinkler （GS）, drip irrigation （DI） andUMDI. After analyzing the reasons caused the differences among four irrigation methodsfrom the potato growth and development and soil water status aspects, UMDI wasselected for further study including the regulation of absorption, translocation andaccumulation for nitrogen （N）, phosphorus （P） and potassium （K）, establishment of thenitrogen diagnostic index and nitrogen fertilization model at the region by reflectancemeter measure value of petiole sap nitrate. The object is to lay the theoretical foundationand provide technical reference for mining the potential of water-saving irrigationtechnology of potato and efficient use of nutrient. The major results of this study are asfollows:1. The potato yield, water use efficiency, light energy use efficiency, N、P and Kfertilizer partial productivity, tuber number per plant, percentage of large tuber, commodityrate, starch content, soluble protein content and net economic income under UMDI and DIare significantly higher than that under FI and GS. Drip irrigation, DI and UMDI, haslower residual soil inorganic nitrogen contents at60～120cm layer after tuber harvestcompared to other treatments, reducing the risk of environmental pollution due tonitrogen leaching. 2. Compared with GS and FI, growth superiority of DI and UMDI appeared at tuberformation stage. At the starch accumulation stage, biomass, leaf area index, the plantheight and the number of compound leaf expressed as DI and UMDI> GS> FI. Dailywater consumption at all irrigation patterns exhibit single-peak curve during the wholegrowth period and the daily water consumption peak occurs at the tuber bulking stage.With0⁸0cm soil profile the average soil water content is shown as: UMDI> DI> GS>FI. The variation coefficients of soil water content at same soil layers under differentirrigation modes are shown as: FI> GS> DI> UMDI.3. N、P and K concentration of the “Kexin No.1” cultivar at different organs declineswith growth processed in the north foot of Yinshan Mountain. The total accumulation ofN, P and K in potato root, stem and leaf exhibits a single-peak curve at whole life cyclebut the accumulation of N, P and K in potato tuber tends to increase with thedevelopment process progressed. The demands of N、P（P2O5） and K （K2O） of “KexinNo.1” cultivar are3.80kg,1.61kg and6.55kg per1000kg tuber separately, at the localenvironmental condition.4. The relationship between yield and N application is more reasonable to fit linearplus plateau model under UMDI. Based on the model the best N application, the nitrogenrecovery efficiency is53.61⁴8.50%and maximum leaf area index is3.72⁴.12at60-day seedlings accordingly.5. The parameters of nitrogen diagnostic index system with reflectometer underUMDI in the north foot of Yinshan Mountain are as follows: the diagnosis time is themorning9¹1; the sampling position is the fourth petioles from the apical tip; thequantity of measurement is30plants at a time. The nitrogen fertilizer recommendationdiagnosis model with nitrate content of the fourth petioles was instituted between18daysto55days of emergence.Nr（18to55days of emergence）=（1.1962Ed²-194.76Ed+10652–Tr）×(2.939×10-6Ed²+3.986×10^-6Ed+0.08256)Among them: Nr: the amount of nitrogen fertilizer (kg·hm^-2); Ed: the day between18to55days of emergence; Tr: nitrate content measured the fourth4petiole （mg·L-1）.