| The northern Anhui Plain,located in the southern part of the Huanghuai Sea,is one of the important grain-producing areas in China.Lime concretion black soil is the main cultivated soil type in this area.The characteristics of this area are sticky,waterlogged,waterlogged,drought and low content of soil organic matter.There are abundant straw resources in this area.In order to reduce the burning and waste of straw resources,straw is used in this area to improve the physical and chemical characteristics of the soil,increase soil fertility,promote the growth and development of Maize in this area,and increase yield.The effects of wheat-jade straw returning on soil structure,nutrient content of 0-40 cm soil layers and growth and yield of summer maize(Zea mays L.)in lime concretion black soil were studied through two-year experiments from 2016 to 2017,in order to provide theoretical basis for improving soil fertility by returning wheat-jade straw to the field.The main results are as follows:1.The total amount of straw returned to the field can effectively improve soil fertility,improve the soil pore structure,significantly increase the nutrient content of 0-20 cm soil layer.The results of 2016-2017 showed that the soil bulk density decreased by 7.38-7.43%and the porosity increased by 9.09-9.73%in the treatment of T2(wheat-jade straw double-season full return+chemical fertilizer)compared with the control T5(straw non-return+chemical fertilizer).The contents of organic matter(SOM),total nitrogen(TN),alkali-hydrolyzed nitrogen(HN),available phosphorus(AP)and available potassium(AK)in the 0-20cm soil layer increased significantly,and each of them increased.The soil nutrient content of group A increased significantly in two years(P<0.05),in which the soil nutrient content in 0-10 cm layer was higher than that in 10-20 cm layer as a whole;the soil nutrient content in T2 treatment was higher than that in T1(wheat straw returning to field in one season+chemical fertilizer)and T4(maize straw returning to field in one season+chemical fertilizer);and the soil nutrient content in 0-40 cm layer was higher than that in non-fertilizer treatment.Chemical fertilizer treatment,especially 0-20 cm soil layer,is the most obvious.2.The total amount of straw returned to the field could significantly increase the trifoliate area,leaf area index(LAI),SPAD value of functional leaves and net photosynthetic rate of maize.The net photosynthetic rate of T2 treatment at heading stage(VT)was significantly higher than that of T5 treatment(P<0.05),increased by 15.52%and 15.63%in 2016-2017,respectively,and the increase was higher than that of single-season straw returned to the field(T1,T4).3.T2 increased maize yield by 12.65-13.17%(P<0.05)compared with T5 treatment in two years,and T1 and T4 increased maize yield by 1.40-7.57%compared with T5 treatment in two years,0.9-3.39%compared with T4 treatment in two years.The yield increase of T1 and T4 treatment with single crop returning to field was not higher than that of T2 treatment in two years.Straw returning to field can increase ear length and grain number per row of maize,increase grain number per ear and grain weight per stick,but has no significant effect on 1000-grain weight of maize.Among them,T2 treatment with double cropping straw returning and chemical fertilizer application has the best effect on increasing yield,and the yield of each treatment with chemical fertilizer application is much higher than that of all treatments without chemical fertilizer application.4.By comparing the results of 2016-2017,it can be seen that under the condition of full mechanization,the total amount of straw comminution and returning to the field can improve the soil structure,improve the soil fertility,promote the growth and development of maize,improve its photosynthetic capacity,increase the number of grains per ear and grain quality,and then promote high yield.Through two years of experiments,it was found that the treatment of wheat-jade straw double cropping returning to the field plus applying chemical fertilizer(T2)was most conducive to achieving high and stable yield of maize crops in this area. |
