| To address the problems of low forage yield and quality,low irrigation water use efficiency and low soil fertility in Wuzhong,Ningxia,this study used "Jingjiu No.26" and "Zhongclover No.3" as the research objects and a two-factor,three-level completely randomised design and controlled experiment to carry out The experimental research on the effects of irrigation and complex oligosaccharides on the growth and soil environmental quality of silage maize and alfalfa in Wuzhong,Ningxia.The study was carried out to investigate the effects of irrigation and complex oligosaccharides on the growth,yield and quality of silage maize and soil in the root zone under different irrigation conditions,to understand the mechanisms of irrigation and complex oligosaccharides on the soil environmental quality of silage maize and alfalfa,and to evaluate and select a health management model for silage maize in Wuzhong based on the TOPSIS multi-objective integrated evaluation model with game-theoretic combination of weights.The results showed that:(1)Both irrigation and oligosaccharide complexes had significant effects on the physiological growth indicators of silage maize.Stem thickness showed a trend of rapid growth-slow growth-stable growth throughout the reproductive period,while the relative chlorophyll content showed an overall rapid growth from seedling to nodulation,decreasing at the stalking stage and slowly stabilising after a slight increase at the spatulation stage.(2)The above-ground fresh biomass showed a gradual increase with the increase in the amount of combined oligosaccharide application,with the high water and high oligosaccharide treatment showing a relatively optimal above-ground fresh biomass increase of about 18.86%compared with the CK(farmer level)treatment.Flooding and oligosaccharide application significantly promoted the growth of maize ears thickness and ears length,with the W3P2(3300 m3/hm2,63 g/hm2)treatment showing the best overall performance of 53.71 mm and 240 mm,an increase of 2.58%and 13.16%respectively compared to the CK treatment(farmer level).(3)Flooding and oligosaccharide application had significant effects on neutral detergent fiber,acid detergent fiber,crude ash,crude protein and crude fat.Neutral detergent fiber performed best at the high water level,and it showed an increase and then decrease with the increase in the amount of complex oligosaccharides applied.At the low and medium water levels,the acidic detergent fiber showed a trend of decreasing and then increasing with the increase of compound oligosaccharide application,and the low water high compound oligosaccharide treatment showed the best performance,which was 15.10%higher than the CK treatment.The crude protein content of maize silage was higher under high water quotas,and crude protein showed a trend of increasing and then decreasing with the increase of complex oligosaccharide application,and all the complex oligosaccharide treatments were higher than CK treatment,higher than 1 8.19%,21.83%and 6.09%,respectively.(4)Under the average level of complex oligosaccharides,the relative forage values under different irrigation were,in descending order,W3>W2>W1;while the relative forage values of different complex oligosaccharide applications under the average conditions were,in descending order,P3>P2>P1.The W3P3 treatment performed best,higher than the CK treatment by 6.52%.(5)Soil urease activity showed an "increasing-decreasing-increasing" trend throughout the fertility period,with the best performance of 1.23 mg·g-1·d-1 at the nodulation stage and the lowest peak of 0.696 mg·g-1·d-1 at the spatulation stage for each treatment at different fertility periods.The fitted curve showed an upward parabola with the highest sucrase activity at the nodulation stage and the lowest sucrase activity at the spatulation stage;at the W1 and W3 irrigation levels,the sucrase activity decreased gradually with the increase in the amount of complex oligosaccharides applied,and at the W2 irrigation level,the sucrase activity showed a decrease followed by an increase with the increase in the amount of complex oligosaccharides applied,and the W3P1 treatment showed the best performance.(6)Soil total nitrogen content showed a trend of decreasing and then increasing with the change of fertility;the overall highest soil total nitrogen content was found at the seedling stage and reached the lowest at the male stage.At the irrigation level of W1,the soil total potassium content showed a trend of increasing and then decreasing with the increase of oligosaccharide application,and the total potassium content of W1P2 treatment was the highest and the total potassium content of W1P3 treatment was the lowest.At the same irrigation level,the soil total phosphorus content increased and then decreased with the increase in the amount of compound oligosaccharide application,and the total phosphorus content of W3P3 treatment was the smallest,which was 7.45%lower than that of CK treatment;at the male tapping stage,the total phosphorus gradually decreased with the increase in the amount of compound oligosaccharide application at different irrigation quotas,and the smallest was 0.79 g/kg in W3P3.At the same irrigation level,the total phosphorus gradually decreased with the increase of compound oligosaccharide application,and W3P3 treatment was 6.90%lower than CK treatment.(7)Each index of maize growth,yield,quality and soil in the root zone was assigned weights by the game-theoretic combination assignment method,in which aboveground fresh biomass was given the greatest weight,crude protein the second and chlorophyll content the least.A comprehensive multi-objective optimization evaluation by applying TOPSIS model found that the W3P3 treatment(3300 m3/hm2,5.6 g/667m2)could be used as a new healthy management model for irrigation and oligosaccharide application to silage maize in Wuzhong,Ningxia.(8)Complex oligosaccharides promoted alfalfa physiological growth(plant height,stem thickness,leaf area and chlorophyll content),yield,quality(neutral detergent fiber,acid detergent fiber,crude protein and crude fat),soil nutrients in the root zone(total nitrogen,phosphorus and potassium)and soil enzyme activity(urease activity and sucrase activity). |
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