Study On Water Consumption Rule And Irrigation Scheme Optimization Of Typical Forage Crops In Agro-Pastoral Ecotone Of Northern China

Agro-pastoral ecotone of Northern China is a transitional zone of agriculture and animal husbandry in northeast China,north China and northwest China,its ecological condition directly relates to the ecological safety of the north and the whole country.Due to the lack of water resources,the development of this region is lagging behind and the ecology is fragile.In order to solve the problem of excessive consumption of water and soil resources caused by high-intensity agricultural production,the state clearly proposes to stabilize agricultural production by"conversion of grain to feeding"and reduce the intensity of water and soil resources development at the same time.In this study,naked oats and silage maize,the main crops in the work of grain conversion to feed,were selected as the research objects.Field experiments were carried out in Zhangbei County,Hebei Province,and combined with the model.The growth process and soil moisture of naked oat and silage maize were simulated based on the Root Zone Water Quality Model 2（RZWQM2）to evaluate the applicability of the model in this region.The evapotranspiration of crops in the field was measured by a large scale lysimeter and its change rule was calculated in each growth period.Fourteen irrigation scenarios were set according to crop growth characteristics and local irrigation policies.The water use efficiency and irrigation water production efficiency of naked oat and silage maize under different scenarios were calculated,and the optimal irrigation scheme suitable for crop growth in this region was determined by comparative analysis.The main results are as follows:1)After calibration of the RZWQM2 model,a set of model parameters suitable for naked oats and silage maize in Zhangbei area of agro-pastoral ecotone of Northern China was determined.The Root Mean Square Error（RMSE）of measured and simulated soil moisture of naked oat from 2018 to 2021 was between 0.005 and 0.043 cm³·cm^-3,and R² ranges from0.681 to 0.992.From 2020 to 2021,the soil water simulation results of silage maize showed that R² was higher than 0.715.The simulation results of plant height,LAI and field evapotranspiration of naked Oat were 2018>2021>2019>2020.The simulation results of LAI and biomass of silage maize were better in 2020.The E,d and R² of plant height in2021 were all higher than 0.950.Field evapotranspiration d in 2020 and 2021 were 0.729and 0.744,respectively.2)The field evapotranspiration of naked oat and silage maize increased first and then decreased during the growth period.From 2018 to 2021,field evapotranspiration of naked oat was the minimum from sowing stage to seedling stage,and the maximum was reached from jointing stage to booting stage,with the maximum daily evapotranspiration of 5.020mm,5.410 mm,4.916 mm and 4.407mm,respectively.From 2020 to 2021,field evapotranspiration of silage maize was the minimum between sowing stage and seedling stage,and the maximum evapotranspiration was achieved when the temperature rose in August,with the average daily evapotranspiration being 3.350 mm and 3.766 mm,respectively.3)When the irrigation volume is 130 mm,field evapotranspiration and yield of naked oat and silage maize reach the maximum.When the irrigation volume is 50 mm（20 mm at sowing stage,30 mm at tasseling stage）,the silage maize yield reach the maximum.The water use efficiency and irrigation water production efficiency reached the maximum when the irrigation amount was 50 mm（20 mm at sowing stage,30 mm at booting stage）,so this model was the optimal irrigation scheme for naked oats.Higher water use efficiency and irrigation water production efficiency can be obtained by irrigating only 20 mm at sowing stage,so this irrigation scenario is the optimal irrigation scheme for silage maize.