西北旱区春玉米滴灌施肥水肥耦合效应研究
Coupling Effects of Water and Fertilizer on Growth of Drip-Fertigated Spring Maize in Arid Northwest China

西北旱区光热资源丰富,利于作物实现高产。然而该地区由于水资源短缺和水肥利用效率较低等问题,发展水肥高效利用的现代农业一直受到制约。近年来,随着农业集约化的推进,西北地区玉米生产发展迅速,采用滴灌施肥技术逐渐增多,在水资源短缺的西北地区,如何利用滴灌施肥技术提高玉米产量和水肥利用效率,对于高效、绿色的现代农业发展具有重要意义。本研究以春玉米为研究对象,于2015年和2016年在中国农业大学石羊河试验站开展了不同滴灌施肥水肥耦合田间试验,以期探索提高水肥利用效率的滴灌施肥模式。利用两年的大田试验,以春玉米“强盛51号”为试验材料,设置4个灌水水平,2015年和2016年分别为I60、I75、I90、I105和I60、I80、I100、I120;4个施肥水平:F60、F120、F180和F240,共16个处理。对不同滴灌施肥水平春玉米生长、产量及构成要素、根系指标、水分利用效率、氮磷钾利用效率、氮磷钾累积量、土壤水分和土壤温度进行了分析,研究了该地区不同滴灌施肥处理春玉米生长特性、干物质累积规律、根系分布规律、土壤水热分布规律及水肥消耗机制,在此基础上,建立了春玉米相对根长密度分布模型,利用HYDRUS-2D模拟和验证了不同滴灌施肥春玉米土壤水热运移规律。具体结果如下:(1)探究了滴灌施肥条件下不同水肥供应对春玉米生长发育和干物质累积的影响机制,并运用主成分分析法对各指标进行了综合评价。2015和2016年不同水肥处理春玉米株高、茎粗均随灌水量和施肥量增加而增加,分别在I105F240和I120F240处理取得最大值。两年LAI均表现出―递增-平台-降低‖的规律。两年根干物质量均随施肥量增加而降低,在F180施肥水平达到最大值,施肥量过大不利于根系生长。从根冠比来看,两年根冠比均随灌水量增加而降低,随施肥量增加先增加后降低,均在I60F120处理取得最大值。作为直接反映作物群体―源-库‖关系的收获指数,2015年和2016年灌水和施肥对春玉米收获指数的影响均达极显著水平(P<0.01)。两年各处理春玉米净同化率(NAR)在整个生育期均呈现出“M”形双峰曲线变化,地上部干物质量符合Logistic生长模型,且拟合结果较优(R2=0.996,P<0.01)。植株生长状况与作物产量的形成紧密相关,运用主成分分析法综合评价春玉米产量与生长指标、水分利用效率、收获指数、净同化率的相关关系,发现地上部干物质、净同化率与产量关系最为密切,灌水和施肥分别在100%105%ETc灌水量与F180施肥量得分最高。(2)优化水肥管理实现了春玉米产量和水肥利用效率的协同提高,并显著降低了肥料损失。春玉米对不同养分的利用效率因施肥量和肥料性质不同而不同,规律表现为磷素>钾素>氮素。就氮肥而言,用量为120 kg N ha-1时,春玉米氮素利用效率最高,当氮肥用量增加到240 kg N ha-1时,氮素利用效率降低了13.1%。磷肥施用范围为3060 kg P2O5 ha-1时,更有利于磷素利用效率的提高。过量施用钾肥会造成植株对钾的奢侈吸收,降低产量,使钾素利用效率降低,当钾肥施用量从30 kg K2O ha-1增加到120 kg K2O ha-1时,钾素利用效率下降了25.2%。春玉米籽粒对不同养分摄取量反应出植株对于养分的需求比例,不同水肥处理春玉米籽粒的氮磷钾摄取量比值平均为1:0.21:0.39。(3)探究了滴灌施肥条件下不同水肥供应对春玉米各生育期根系分布规律,建立了考虑水肥耦合下春玉米相对根长密度分布模型。春玉米各生育期根系特征参数与产量和地上部总干物质量均呈显著相关关系,相关系数大小按生育期排序表现出灌浆期>大喇叭口期>成熟期>小喇叭口期规律,保证大喇叭口至灌浆期合理的水肥供应最为重要,其次是小喇叭口至大喇叭口期,播种至小喇叭口期和灌浆至成熟期2个生育阶段有较大的节水节肥潜力。建立滴灌不同水肥供应春玉米相对根长密度(NRLD)分布模型,发现春玉米NRLD与土壤相对深度呈现显著的三阶多项式函数。运用NRLD分布模型估算相对深度根系分布比例,从估算结果可以看出,根系主要集中于表层土壤,地表至相对根系扎深1/3处根长占总根长比例平均达73.6%,地表至相对根系扎深1/2处根长占总根长比例达82.8%。(4)揭示了不同水肥供应春玉米根区土壤水分和土壤温度的时空分布规律,并基于HYDRUS-2D模型模拟和验证了滴灌施肥条件下玉米农田的水热运移规律。不同灌水量春玉米小喇叭口至成熟期土壤表层下5 cm日均温度差异显著。同一灌水处理不同土层在苗期取得最大温差,拔节期次之。T1点土壤温度离散程度要大于其他位置点,中位值随着土层深度的增大而降低;相同位置土壤温度中位值随着灌水量的增加而降低。采用HYDRUS-2D模型模拟滴灌春玉米土壤水热运移,发现土壤含水量和土壤温度模拟值与实测值吻合度较好。I60、I75、I90和I105灌水处理0-20 cm土层土壤含水量模拟值与实测值n-RMSE介于11.921.3%,其他土层模拟值与实测值n-RMSE均小于20%。表层土壤(5cm)土壤温度的RMSE随着灌水量增加而降低,其他土层RMSE随着灌水量增加先降低后增加,均在I90处理取得最小值。土壤温度标准差化均方根误差(n-RMSE)除了I60处理在表层土壤5cm处大于10%(为14.0),其他灌水处理各土层均小于10%,模拟效果均为极好水平。(5)研究分析了滴灌施肥条件下春玉米产量、干物质量、水分利用效率、肥料偏生产力及经济效益指标的水肥耦合效应。基于最小二乘法原理,建立和求解了单目标的二元二次方程,2015年和2016年灌水量和施肥量作为自变量的春玉米产量、地上部干物质量、WUE、PFP和净收益的二元二次回归方程均达极显著水平(P<0.01),决定系数均在0.8以上。运用二元二次回归和归一化处理相结合的方法,2015年和2016年灌水量分别为452(110%ETc)和449(98%ETc)mm,施肥量分别为190-95-95和178-89-89(N-P2O5-K2O)kg/ha,可以使春玉米产量、WUE和净收益的综合效益最大化。

An abundance of light and heat resources in the arid regions of northwestern China is conducive to high yields of the crops.However,due to water shortages and low use efficiency of water and fertilizer in this region,modern agriculture that develops efficient use of water and fertilizer was constrained.In recent years,with the advancement of agricultural intensification,maize production in the northwest region has developed rapidly,and the application of drip irrigation has gradually increased.In the northwestern region of China,where water resources are scarce.Thus,how to use drip fertigation technology to improve maize yield and water and fertilizer use efficiency is of great significance for the development of efficient and green modern agriculture.In this study,spring maize(Qiangsheng 51)was tested.A field experiment was conducted during 2015 and 2016growing seasons at Wuwei Experimental Station for Efficient Use of Crop Water,Ministry of Agriculture,northwest China.In order to explore drip irrigation and fertilization modes for improving water and fertilizer use efficiency of maize.Using ’Qiangsheng 51’ as the test cultivar,the field experiment was subjected to four water supply levels,I60,I75,I90and I105 in 2015,and I60,I80,I100 and I120 in 2016,were in interaction with four fertilization levels that based on different ratios of N-P2O5-K2O,i.e60-30-30,120-60-60,180-90-90 and 240-120-120 kg/hm2,ETc is the average annual crop evapotranspiration.This resulted in 16 treatments.The effects of different drip irrigation and fertilization levels on the growth,yield and components,root indicators,water use efficiency,NPK use efficiency,NPK accumulation,soil moisture and soil temperature were analyzed.The growth characteristics,dry matter accumulation,root distribution,soil water and heat distribution,and water and fertilizer consumption mechanisms of spring maize under different levels of drip irrigation were studied.Moreover,the relative root length density distribution model of spring maize was established.The HYDRUS-2D was used to simulate and verify the soil moisture and heat transfer patterns of different drip irrigation fertilization spring maize.Following are the main achievements of this thesis:(1)The effects of different water and fertilizer supplies on spring maize growth and dry matter accumulation under drip fertigation conditions were investigated.And each parameter was comprehensively evaluated using the Principal Component Analysis method.The plant height and stem diameter of spring maize with different water and fertilizer treatments increased with the increase of irrigation and fertilization levels,and the maximum values were found in I105F240 and I120F24040 treatments in 2015 and 2016,respectively.In the two years,LAI showed the law of "increasing-platform-lowering".The quality of root dry matter decreased with the increase of fertilizer application rates,and reached the maximum at F180.The excessive application of fertilizer was not conducive to root growth.From the ratio of root to shoot,the ratio of root to shoot decreased with the increase of irrigation amount,and increased first and then decreased with the increase of fertilizer application,and the maximum value was obtained in I60F120 treatment.As a harvest index that directly reflects the "source-library" relationship of crop groups,the effects of irrigation and fertilization on spring maize harvest index were extremely significant(P<0.01)The net assimilation rate(NAR)of spring maize showed an "M"-shaped double-peak curve change during the whole growth period.The dry matter quality of the above-ground part was consistent with the Logistic growth model,and the fitting result was superior(R2=0.996,P<0.01).Plant growth status is closely related to the formation of crop yield.Principal component analysis was used to comprehensively evaluate the correlation between spring maize yield and growth index,water use efficiency,harvest index and net assimilation rate.It was found that the above-ground dry matter,net assimilation rate and yield were most closely related.The highest score of irrigation and fertilization were achieved by100%105%ETc and F180 fertilization,respectively.(2)Optimized water and fertilizer management achieved a synergistic improvement in spring maize yield,as well as water and fertilizer use efficiency.Moreover,it significantly reduced fertilizer losses.Optimized water and fertilizer management achieved a synergistic improvement in spring maize yield and water and fertilizer use efficiency,and significantly reduced fertilizer losses.The utilization efficiency of different nutrient by spring maize varies with the amount and nature of fertilizers and it follows the order:P>K>N.In terms of nitrogen fertilizer,the nitrogen utilization efficiency of spring maize was the highest when the dosage was 120 kg N ha-1.When the nitrogen fertilizer dosage increased to 240 kg N ha-1,the nitrogen use efficiency decreased by 13.1%.When the application range of phosphate fertilizer is 30-60 kg P2O5 ha-1,it was more conducive to the improvement of phosphorus utilization efficiency.Excessive application of potassium fertilizer will caused absorb the luxury of potassium in plant,reduced the yield and the utilization efficiency of potassium.When the application rate of potassium fertilizer increased from 30 kg to 120 kg K2O ha-1,the utilization efficiency of potassium decreased by 25.2.%.Spring maize kernels responded to different nutrient intakes indicated the proportion of nutrients required by the plants.The average absorptions of N,P and K by 100 kg grains treated under different irrigation and fertilization conditions were 1.00,0.21,and 0.39,respectively.(3)The distribution of roots of spring maize at different growth stages was studied under different drip fertigation conditions.The relative root length density distribution model of spring maize under water and fertilizer coupling was developed.There were significant correlations between root characteristics parameters and yield and total dry matter quality of spring maize at different growth stages.The correlation coefficients followed the order:filling stage>12 collars stage>maturity stage>6 collars stage.The effects of root distribution on maize yield and dry matter mass were maximized during the grain filling period,followed by 12 collars.A normalized root length density(NRLD)distribution model of spring maize was established to describe NRLD distribution under different water supply and fertilization levels under drip irrigation.Overall,the length of root from ground to the upper 1/3 of the underground part accounted for 73.6%of the overall root length,and the length of root from ground to the upper 1/2 of the underground part accounted for82.8%of the overall root length.(4)The temporal and spatial distribution of soil moisture and soil temperature in spring maize root zone with different water and fertilizer supplies was revealed.The water-heat migration pattern of maize farmland under drip fertigation conditions was simulated and validated based on HYDRUS-2D model.The irrigation conditions had a significant effect on the daily average temperature of 5cm below the surface from the 6 collars to maturity stage of spring maize.The temperature difference in all soil layers by one specific irrigation treatment was maximized at the seedling stage,followed by the 12 collars.The discrepancy of soil temperature was maximized at point T1,while the median soil temperature decreased as the soil depth increased.In a specific soil layer,the median soil temperature decreased as the irrigation volume increased.The water and heat transfer in soil for spring maize under drip irrigations was simulated using the HYDRUS-2D model and the results indicated good consistence of the simulated soil water content and soil temperature and the measured values.The n-RMSE of simulated and measured water content in the 0-60 cm soil layer by I60,I75,I90and I105 treatments were between 11.9%and 21.3%,while those in other soil layers were below 20%.The RMSE of temperature in surface soil(0-5 cm)decreased as the irrigation volume increased,while that in other layers decreased and then increased as the irrigation volume increased.The RMSE of temperature was minimized by I90 treatment in all layers.The n-RMSE of soil temperature were less than 10%in all layers by all treatments,except for the 5 cm of surface soil by I60 treatment(14.0),indicating excellentsimulation performance.(5)The water-fertilizer coupling effect on spring maize yield,dry mass,water use efficiency,fertilizer partial factor productivity,and economic benefit indicator was analyzed under drip fertigation conditions.In terms of coupling of water and fertilizers,the binary quadratic regression equations of spring maize yield,ground dry matter mass,WUE,PFP,and net income with irrigation volume and fertilizer amount as independent variables reached extremely significant levels(P<0.01)and the coefficient of determination was above 0.8 in 2015 and 2016.Using the binary quadratic regression method and normalization,it was demonstrated that the overall benefits of spring maize yield,WUE,and net income were maximized at irrigation volumes of 452(110%ETc)mm in 2015 and 449(98%ETc)mm in 2016 and fertilization of190-95-95(N-P2O5-K2O)kg/ha in 2015 and 178-89-89(N-P2O5-K2O)kg/ha in 2016.

春玉米; 滴灌施肥; 产量; 根系; NRLD分布模型; 水肥利用;

Spring maize; Drip fertigation; Yield; Root system; NRLD distribution model; Water and fertilizer use efficiency;

国家“十二五”863计划课题“农田水肥联合调控技术与设备”(2011AA100504); 国家“十二五”科技支撑计划“黄土高原扬黄灌区(宁夏)增粮增效技术研究与示范”(2015BAD22B05);

张富仓; 范军亮;

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9221798188K