| Water shortage has become the bottleneck of social and economic development.In arid areas,there are several problems such as uneven distribution of water resource,irrigation water can only satisfy partly water management in agriculture.Agricultural water saving technology can improve the efficiency of agricultural water production,it has become a hot research topic in the field of agricultural soil and water resource in arid area.This paper takes summer maize with drip irrigation as the research object.In this study,carbon stable isotope technique,dual crop coefficient and other methods were used to analysis the effect of water consumption characteristics of summer maize with mulch or non-mulch as well as the growth index of different water and nitrogen treatments with drip irrigation for 2 years experiments.And based on the DSSAT-CERES-Maize model,the optimal water and nitrogen management patterns of summer maize with drip irrigation were chosen.Conclusions are as follows:(1)In 2016 and 2017,soil moisture have presented obvious spatial and temporal variation characteristics with mulch or non-mulch in full reproductive period of summer maize.The soil moisture declined with the advancement of the growth.The surface soil moisture is the lowest.With the increase of soil depth,the variation trend has become increased and then reduced.The soil layer between 10?70 cm had a greater influence on the moisture content to maize root system.The soil moisture presented decline between 70?100 cm soil layer.(2)Summer maize transpiration(T)and evapotranspiration(ET)were estimated by the dual crop coefficient approach.Evapotranspiration was validated,and a positive regression with those values was obtained using the water balance method,with a root mean square error(RMSE)of 10 mm.The estimated transpiration also had a positive regression with measurements obtained by the stable carbon isotope technique,with a RMSE of 20 mm.By analyzing the RMSE,regression coefficients,and concordance index,we suggest that the dual crop coefficient approach is an effective method to estimate and partition evapotranspiration.Across the entire growing season for partially mulched summer maize,estimated crop transpiration accounted for 78.7%and 76.0%of the total evapotranspiration in 2016 and 2017,respectively.The values of T/ET with non-mulched was 10.65%?18.25%less than that of partial mulched crops,which indicated that mulching improved the values of T/ET.(3)The value of SPAD,LAI,plant height and dry matter accumulation quantity had the same variation tendency with mulch in 2016 and 2017.Under the condition of different irrigation amount,each index showed a trend of increase with the higher irrigation amount.With the increase of nitrogen application rate,each index showed a trend of increases and then decline with the condition of different nitrogen application.Under the condition of different irrigation frequency,each index showed a trend of increase with the higher irrigation frequency.Contrast mulch and non-mulch condition,the average values of SPAD,LAI,plant height and total dry matter accumulation amount in the whole stages with mulch is higher than non-mulch 18.3%,41.6%,11.3%and 57.1%respectively in 2017.It means that mulch can promote crop growth effect is obvious.(4)Under the condition of different irrigation quota,the treatment W1N2 can obtain higher yield(16677kg·hm-2 and 15517kg·hm-2 with mulch and non-mulch respectively)in 2016 and 2017.Under the condition of different nitrogen application,the treatment N2W2(nitrogen application rate of 278.4kg·hm-2)can obtain higher yield(15459kg·hm-2 and 13392kg·hm-2 with mulch and non-mulch respectively).Different irrigation frequency on yield of summer maize had a certain impact,but the difference was not significant.The yield with mulch in 2017 is higher than non-mulch about 26.3%.The nitrogen content of maize leaves and stems declined with the development of growth period.Under the condition of different irrigation quota,plant nitrogen accumulation amount(NAP),nitrogen uptake efficiency(NUPE),nitrogen harvest index(NHI)and nitrogen production efficiency(NPE)showed increased with the higher quota of irrigation water.Under the condition of different nitrogen application,the value of NAP,NUPE and NPE showed increased with the higher quota of nitrogen application.Contrast effect to nitrogen use efficiency with mulch and non-mulch,those indexes can be improved effectively with mulch.(5)The model of DSSAT-CERES-Maize was used to simulate the values of phenophase,aboveground biomass and grain yield of summer maize.The results showed that,the simulation of phenological phase has a high precision,but the simulation of the aboveground biomass and grain yield has a medium precision.The optimal water and nitrogen management pattern can be found based on this model.The result is:the irrigation amount is 160mm,nitrogen application rate is 200 kg·hm-2 can get a higher yield(8588 kg·hm-2).In this pattern can achieve the effect of saving water and fertilizer. |
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