Effects Of Planting Cover Crops On Weeds Control And Soil Environment In Citrus Orchard

Orchard cover crops is planted in the orchard with suitable cover crops species,and fruit trees in harmony and symbiosis.Orchard cover crops can inhibit the growth of weeds,is a means of green weed control,but also a source of organic matter input to the orchard,to play the effect of green fertilizer.In this experiment,we investigated the use of the graminae(Vulpia myuros)and the legumes(Vicia villosa)and(Vicia sativa).The experiment was divided into two stages.In the first stage,the above three orchard cover crops were trialed in different areas of the citrus producing areas in Sichuan to observe the effects of the three orchard cover crops on weed control and soil nutrient content in different areas.The second phase was set to compare the effects of planting three types of orchard cover crops with common field weed treatments(hand mowing,mulching ground cloth,herbicide weed control)on the soil environment.The main findings of the study are as follows:(1)The biomass of the three orchard cover crops varied considerably in the different regional citrus parks,with Vicia villosa having the highest biomass,followed by Vicia sativa,and Vulpia myuros having the lowest biomass.A survey of the biomass of orchard cover crops in different growth periods revealed that the highest biomass was found in March of the following year after planting.The results of the sample cover and weed observations showed that Vicia villosa and Vicia sativa provided rapid ground cover and weed control in the early stages after sowing,while Vulpia myuros L.maintained a high cover in the later stages.Comparing the effects of planting in different areas,the results showed that the biomass and cover of the three orchard cover crops in the Suining sample plot were better than those in the other four areas.(2)Soil measurements from orchard cover crops trials in different areas showed that the 0-20 cm soils planted with the three orchard cover crops contained higher organic matter,alkaline soluble nitrogen,effective phosphorus and fast-acting potassium in general than those with herbicide applications.The effect of planting Vicia villosa and Vicia sativa.on the organic matter and alkaline nitrogen content of the soil was slightly better than that of planting Vulpia myuros,with significant differences in the Suining and Langzhong trials.The planting of Vulpia myuros had a tendency to increase the effective phosphorus and fast-acting potassium content of the soil,especially in the Guang’an and Gulin trials.20-40 cm soils showed little difference in soil nutrients between treatments.(3)In a sentinel trial(Suining area),the effects on the soil environment of planting three types of orchard cover crops versus common weed control methods(hand mowing,herbicide weeding and mulching with ground cloth)were compared.The results showed that the soil organic matter content,alkaline decomposed nitrogen and phosphorus and potassium content were significantly higher in the 0-20 cm soil layer with orchard cover crops than with hand mowing,herbicide mowing and mulched ground cloth.Sucrase,catalase,phosphatase and urease activities were also generally higher in orchard cover crops soils than in soils with common weed control methods,with sucrase and urease activities being highest in glossy purple crocus soils,phosphatase activity highest in Vulpia myuros L.soils and catalase activity significantly different in the three orchard cover crops soils.The most dominant types of soil microbial communities at the fungal genus level in each treatment were Fusarium and Mortierella,and the main groups at the species level were Fusarium solani,Mortierella alpina,Humicola olivacea and others.Soil microbial diversity was significantly higher in orchard cover crops citrus orchards than in hand mowed,mulched ground cloth and herbicide weeded.(4)The results of the redundancy analysis between the fungal community and soil environmental factors showed that the composition of the orchard herbaceous microbial community was significantly influenced by soil N,P,K and phosphatase,sucrase and urease activities,with the planting of arrow pea and Vulpia myuros having a greater impact on soil N,P,K content,soil enzyme activity and soil microbial diversity.The manual mowing and ground cloth treatments were positively correlated with soil NPK content,as were soil phosphatase,sucrase and urease activities,while the herbicide treatments were negatively correlated with soil NPK content.