Effects Of Irrigation And Fertilization On Alfalfa Seed Production Performance And Soil Physical And Chemical Properties

In order to study the optimal irrigation amount and fertilizer ratio of alfalfa seed production in semi-arid area of Ningxia,reduce the waste of water resources and fertilizer,improve production efficiency,and provide theoretical reference for alfalfa seed production in semi-arid area of Ningxia.In this experiment,alfalfa ’Zhongmu No.3’ was used as the test material,and the split-plot experiment design was used.Four irrigation gradients(600,900,1200 and 1500 m3·hm-2)were the main areas,and four fertilization gradients(N-P2O5-K2O:14-36-40,28-72-80,42-108-120,56-144-160 kg·hm-2)were the sub-areas.During the seed growth period,the seed yield,yield components,seed quality and soil physical and chemical properties were measured.The main results are as follows:1.Water and fertilizer regulation had significant effects on seed yield and yield components of alfalfa.When the seed yield reached the maximum,the combination of water and fertilizer was W2F3.When the irrigation amount was 900 m3·hm-2 and the fertilization amount was N-P2O5-K2O(42-108-120 kg·hm-2),the maximum yield was 855.31 kg·hm-2,and the irrigation water use efficiency under this treatment was slightly lower than the maximum.Path analysis showed that the number of reproductive branches,pod setting rate and inflorescence number were important yield components affecting seed yield.2.The effect of fertilization on seed quality was greater than that of irrigation.Under the same irrigation gradient,different ratios of nitrogen,phosphorus and potassium had significant effects on seed quality traits.F3(42-108-120 kg·hm-2)had the best seed quality,and irrigation and fertilization had a certain interaction effect on alfalfa seed quality.When the irrigation amount was 1200 m3·hm-2 and the fertilization amount was N-P2O5-K2O(42-108-120 kg·hm-2),the seed quality was the best.3.The interaction of water and fertilizer can reduce soil pH,and the appropriate proportion of water and fertilizer can reduce soil bulk density,increase soil porosity and improve soil organic matter content.Comprehensive analysis of soil properties showed that the combination of irrigation 1500 m3·hm-2 + fertilization N-P2O5-K2O(42-108-120 kg·hm-2)had relatively better soil quality,and there was a significant correlation between soil factors and seed yield.4.The optimal treatment for grey correlation comprehensive analysis is W2F3.In summary,in the process of alfalfa seed production in semi-arid area of Ningxia,the combination of irrigation amount 900 m3·hm-2 and fertilization amount N-P2O5-K2O(42-108-120 kg·hm-2)is beneficial to improve the quality and income of alfalfa seeds,and the irrigation water use efficiency and fertilizer partial productivity under this combination of water and fertilizer are significantly improved.It is also an effective combination of water and fertilizer for soil improvement.