The Returning Effect Of Amaranthus Hypochondriacus On Soil Fertility And Nutrients Uptake Of Tobacco

A. hypochondriacus was used as potassium rich green manure, and in tobacco production has a broad application prospect. The effect on soil nutrient and tobacco nutrient uptake that A. hypochondriacus applied in tobacco-leaf production need to be undersand. By in situ incubation experiment, the regularity of nutrient release of A. hypochondriacus was nanlyzed. Using potted plant experiment, the nutrient cycle in A. hypochondriacus-tobacco growing system to studyed. Through two years of field experiment, in order to analysis before grain amaranth-plant returning or after influence on soil nutrient and tobacco nutrient absorption. By the study of returning effect of amaranthus hypochondriacus on soil fertility and nutrients uptake of tobacco, we attempt to establish vega plant using A. hypochondriacus green manure mode. Main results are followed:1. The results show that in the first 14 days after A. hypochondriacus returning to the soil, the concentration of soil DOC, Nmin, available potassium and slow-release potassium increased significantly comparing to the control; Apparent nitrogen release rate of grain amaranth reached about 19.5%, and the apparent potassium release rate reached above 63.4%. After 14~56 d incubation, the order of soil Nmin, available potassium, slow-release potassium concentration between treatments and control is 45 d-harvest>55 d-harvest>65 d-harvest>Control, but there were no significant differences between the treatment and control in soil NH4+-N(Removal of the treatment of 45 d-harvest) and DOC concentration. After 56 days incubation, the Nmin concentration in the treatments is at least 3.4 times higher than contrast, available potassium concentration is at least 3.1 times higher than the control, slow-release potassium is at least 1.1 times higher than the control. Among the treatments, 45 d-harvest has smaller nitrogen and potassium apparent release rate than the treatments of 55 d-harvest and 65 d-harvest during the incubation time. In conclusion, grain amaranth returning to soil can obviously improved the soil available nutrients after 14 days. and 45 d-harvest of A. hypochondriacus has better effect on soil improvement compared to other treatment.2. Between 35 d and 45 d after A. hypochondriacus seeding, N, P and K nutrients of plant of A. hypochondriacus are rapid accumulated, and N, P, K nutrient accumulated slowly after sowing 45~55 d. compared to the CK, the treatment A. hypochondriacus-growth 55 d, A. hypochondriacus-growth 45 d and A. hypochondriacus-growth 35 d, soil Nmin concentration decreased, available P, available K increased, and slow-release K has no significant changing. After tobacco transplanting 45 d and 60 d,A55(A. hypochondriacus-growth 55 d turned down), A45(A. hypochondriacus-growth 45 d turned down), A35(A. hypochondriacus-growth 35 d turned down) compare with CK(Do not grow A. hypochondriacus turned down) had no significant changing on Nmin, available P, available K and slow-release K concentration. While C+A45(with give A45 equivalent of the same A. hypochondriacus) soil nutrients were higher than CK. The nitrogen, phosphorus and potassium concentration and accumulation in the root, stem, lower, middle, upper leaves of tobacco plant did not differ significantly between the treatments. The treatment of A55, A45, A35 and C+A45 tobacco plant dry matter weight increased more than 32.7% than CK; The accumulation of N, P and K nutrient are at least higer 33.2%, 18.8%, 25.9% than CK. In addition, the nutrient accumulation is minimum in A35 and is maximum in C+A45, and nutrient accumulation of difference is mainly manifested in the leaf.3. In the model tobacco-A. hypochondriacus interplanting, interplanting A. hypochondriacus processing, the tobacco soil alkaline hydrolysis N reduce more than 22%, and alkaline hydrolysis nitrogen consentration of interplanting A. hypochondriacus-growing 45 d returning to soil processing compared with not returning to soil processing higher 5.4%. the soil available P, available K was all increased compare to the control, especially available K increases in 10.5% ~ 32.6%, but soil slow-release K did not changed. Dry matter of tobacco plant, N, P and K accumulation in tobacco plant are not affected by significantly. But the concentration of P, K of tobacco leaf were increased, addition of tobacco leaf potassium content can reach 12.0%.4. in the model of tobacco-A. hypochondriacus interctropping, after A. hypochondriacus returning, the soil available K and soil slow-release K content were increased significantly, especially available K increases in 54.0% ~ 91.1%, but the soil slow-release K did not changed. Dry matter of tobacco plant, N, P and K accumulation of tobacco plant are not affected. But the concentration of N, P, K of tobacco leaf were increased compared with tobacco monoculture, it should be pointed out that, the K concentration in lower leaves, middle leaves, upper leaves can increased 12.6% compared with tobacco monoculture.