中文摘要：

为了增加方形地块四角的灌溉面积,工程应用时经常在圆形喷灌机末端安装尾枪,而尾枪周期性地关闭和打开会改变喷灌机入机流量,导致喷灌施肥均匀性降低。为此本文设计了基于北斗技术控制尾枪开闭的圆形喷灌机变量施肥系统,并以安装D3000低压喷头和P85A摇臂式喷头为尾枪的圆形喷灌机为对象,研究了在尾枪关闭和打开两种工况下变量喷灌施肥均匀性。结果表明,圆形喷灌机行走状态下,尾枪关闭和打开两种工况时喷灌施肥均匀C＊（UH）系数为66.1%-68.4%,电导率变异系数CV为0.9%-3.7%;圆形喷灌机停止状态下,尾枪关闭和打开两种工况时克里斯琴森均匀系数CU为98.2%-99.2%,电导率变异系数CV为0.9%-2.1%。试验过程中尾枪定位和开闭切换由变量施肥系统自动控制,表明研发的变量施肥系统运行稳定可靠。

英文摘要：

In order to increase irrigation area at four corners of a square field,an end gun is often installed on a center pivot irrigation system in practice.As the end gun periodically closed and opened,the inlet flow rate of the system changed accordingly,which might decrease the resultant fertigation uniformity.In this study,a variable rate fertigation system was designed based on the Beidou system whose receiver was equipped on center pivots with end guns.The center pivot irrigation system was equipped with low-pressure D3000 sprinklers and a P85A type impact sprinkler as the end gun.Tests of fertigation uniformity were carried out under the conditions of end gun closed and opened.The results indicated that when the center pivot system was running,the Heermann-Hein uniformity coefficient C_（UH）~＊ and the variation coefficient Cv of fertigation were 66.1%to 68.4% and 0.9% to 3.7%,respectively.And when the center pivot system was fixed,the Christiansen uniformity coefficient Cv and the variation coefficient Cv of fertigation were 98.2% to 99.2% and 0.9% to 2.1%,respectively.During the test,the end gun was automatically positioned and switched on/off by the variable rate fertigation system.In general,the fertigation system developed in this study works stably and reliably.