Study On Planting Technique And Decomposition Character Of Several Green Manure Crops

The effect of sowing date, seeding quantity, phosphate fertilizer amount, soil moisture on the growth and development condition, yield, nutrient absorption and accumulation of green manure were investigated in this study using pot experiment and field experiment. The laws of growth, nutrient absorption and accumulation of smooth vetch, wheat and rape were studied by mixed cropping. The green manure were wrapped in net nylon bags and mulched to the fields in order to investigate the characteristics of decomposing and nutrients released rules. These studies hope to provide theoretical and technical basis for the production and utilization of green manure in dry land. The main results were showed as follows.(1) Plant growth and fresh yield of green manure were respectively investigated with different seeding quantity under field and bonsai test condition. The nutrient absorption and accumulation rules also were analysised in different growth stages. The results showed that:with quantities of seeds increased the emergency number increased, the plant height, leaf length, leaf width, compound leaves increased and then decreased with continue increasing seeding rate. There was no significant influence of seeding quantity on nutrients content, but had obvious effect on nutrients accumulation. All nutrients accumulation increased as the seeding quantity increased in the first183days after sowing. All nutrients accumulation were the most at208days after sowing. The nutrients accumulation of Smooth vetch were characterized as seeding quantity with60kg/hm2> seeding quantity with90kg/hm2> seeding quantity with120kg/hm2> seeding quantity with30kg/hm2. The nutrients content and accumulation trends of Villous vetch and Common vetch were same to Smooth vetch. The study showed that the optimum sowing quantity of smooth vetch is60～90kg.hm-2, the villous vetch is75～112.5kg.hm-2, the common vetch is180～240kg.hm-2.(2)Sowing date significantly affect the growth, development, fresh yield and nutrient accumulation. The results showed that the shoot height, compound leaves per plant, branches per plant decreased as the sowing date postponed, the seeding emergence time extend from3days to15days. Fresh yield and nutrients accumulation decreased as the sowing date postponed. Sowing date at13th October get the highest yield, compared with the Sowing date24th November, aboveground production increased by51.2%. The study showed that the first ten-days period of October was the best sowing date under this condition of experiment.(3)A pot experiment was conducted to investigate the impact of different soil moisture on seeding emergence, growth and development, nutrient accumulation of smooth vetch. The results showed that, the soil water holding capacity was between70%～80%,which benefit to the seeding emergence. In the blooming stage, the fresh yield, nutrient absorption and accumulation can reach the maximum.(4)The test was proceeded in pot with wheat, rape and Smooth vetch, in which the ratio of wheat, rape to Smooth vetch was1:9,3:7and1:1. The results showed that in the blooming stage of Smooth vetch, single-sowing and mix-sowing with different proportion have different yield. The biomass of90%Smooth vetch mix-cropping with10%wheat,70%Smooth vetch mix-cropping30%with wheat and90%Smooth vetch mix-cropping with10%rape could get higher biomass than Smooth vetch monoculture, but wheat and raps’biomass decreased with the Smooth vetch mixture proportion increased. Each mixture of wheat with Smooth vetch had higher total N, P, K content compared with the Smooth vetch monoculture; Smooth vetch mix-sowing with rape, the phosphorus were less than the Smooth vetch monoculture. The N, P, K, C accumulation of Smooth vetch monoculture in shoots was characterized as minimum. In the same proportion of Smooth vetch in mixed cropping conditions, treatment of Smooth vetch mix-cropping with wheat get higher amount of N and K accumulation than the treatment of Smooth vetch mix cropping with rape, but the P accumulation. In conclusion, the best mixture planting proportion was in ratio of70%Smooth vetch to30%wheat or30%rape.(5)The field experiment was carried out to study the influence of different phosphorus fertilizer amount on the grow index, fresh yield, the nutrients uptake and accumulation of Smooth vetch. Villous vetch and Common vetch. Results showed that application of phosphate fertilizer significantly increased the yield of three green manure crops. Application of phosphate fertilizer at rates of45～90kg·hm-2gave an fresh yield increase of74.59%～114.84%for smooth vetch and86.18%～126.12%for Villous vetch and50.5%～179.81%for Common vetch. The dry matter accumulation intensity of the green manure crops had reached maximum when application of phosphate fertilizer at rate of90kg·hm-2.The plant total N, P, K content of green manure were increased gradually with the increase of phosphate fertilizer rate, however, the C content was not significantly related to phosphate fertilizer amount. The N, P, K, C accumulation increased as the phosphate fertilizer application increased, then at high phosphate fertilizer level, the nutrients accumulation were the most.(6) In order to investigate the characteristics of decomposing and nutrients released rules, the nylon mesh bag method was used to monitor the nutrient releases from the manures of Smooth vetch, Villous vetch, Chinese milk vetch and Common vetch to soil in112days in submerged condition and drought conditions. The results showed that the four green manures have an initial rapid decaying and then slowly decrease with time. After112d, the cumulative decomposing rates are75.63%,72.35%,74.55%and61.83%respectively in submerged condition; in drought conditions, the decomposition rate of the villous vetch and Chinese milk vetch were80.13%and70.57%. The decomposition of Smooth vetch, Villous vetch and Common vetch was mainly concentrated in the initial15days or20days, the Chinese milk vetch was decomposed fast in the first35days after incubation. Cumulative release amount expressed as Smooth vetch>villous vetch>Common vetch>Chinese milk vetch, however, the cumulative release rate has no significant difference. Release rates of the nutrients of the crops are different, the K release rate is considerably greater than the rates of P and N releases. After112days of incubation, the cumulative release rate of C, N, P were56.87%～80.47%;72.35%～91.87%56.01%～95.1%, the cumulative release rate of K is higher than90%. In drought condition, the cumulative release amount and the cumulative release rate of Villous vetch are higher than Chinese milk vetch. The submerged condition is more conducive to the release rates of the nutrients than the drought condition.