| Grain amaranth is a kind of K rich green manure,and tobacco is a kind of potassium fertilizer.Therefore,the grain amaranth has certain application prospect in tobacco production.In order to play the effect of fertilizer better,this study mainly aiming at different sowing time and different degree of grinding to analysis the growth law and nutrient accumulation law(including N?K)of grain amaranth under different sowing times.And analysis N?K nutrient release and migration during decomposition process at different grinding of grain amaranth.Grain amaranth R104 nitrogen content in 3%above.In this study,the effects of N application on grain amaranth was studied,and the absorption of N from soil,N source and grain amaranth was analyzed.The result as follows:1.The growth and nutrient accumulation of grain amaranth showed"S"curve.In the early stage,the growth rate was slow,and the growth rate was accelerated after 30d.At the later growth stage,the leaves fall off from plant.From the plant height,leaf growth and dry matter accumulation rate,there was a difference in the time of rapid growth of grain amaranth at different sowing dates.In general,the faster the sowing time was,the faster the growth period was.N and K content in grain amaranth was consistent in root and stem leaf dynamics,as growth were decreased.T1(Sowing date was April 8th)and T2(Sowing date was April 23rd)had no significant difference,which were greater than those of T3(Sowing date was May 8th)treatment.The change rules of N content and K content showed increase and then decrease.N content and K content in root,stem,leaves of T3 were significantly lower than T1,T2 treatment.Plant growth and nutrient accumulation in accordance with Logistic growth curve,which can be concluded that the accumulated temperature of the dry matter accumulation rateo reached the maximum is 1170.50?,and the accumulation rateo of N?K are 997.25?and 1053.75?,respectively.2.The release rate of N and K in the process of decomposition grain amaranth was faster than that in late stage.15 days before returning was the rapid release phase of N and K.After 34 days,the release rate of N and K in the stalk of grain amaranth reached to 72.8%and 94.2%respectively.And the maximum apparent transformation rate of N in grain amaranth to Nmin in soil was only 12%,while the apparent transformation rate of K to available K was 69.8%.The change of N and K in soil was different after the grain amaranth's stalk returning with different grinding degrees.The content of NH4~+-N and rapidly available K in soil was present as T3(adding particle size was 5 cm±0.5 cm grain amaranth's stalk)>T2(adding particle size was 3 cm±0.5 cm grain amaranth's stalk)>T1(adding particle size<2 mm grain amaranth's stalk).The content of Nmin in soil was present as T1>T2>T3,the slowly available K in soil had no obvious distinction among treatments.Thus the following conclusions of this study:the apparent transformation rate of N in grain amaranth to Nmin in soil was far less than that of K to available K.The bigger of reduction radio of grain amaranth's stalk is better for increasing of Nmin in soil,while the smaller of reduction radio of grain amaranth's stalk is better for rapidly available K in soil.3.Reducing the application of N fertilizer for 20%(A2)could increase the utilization rate of N fertilizer.The application of grain amaranth and N fertilizer(A3)could promote the absorption of N from grain amaranth in the early stage(V9)and late(V12+10d).Treatment of grain amaranth and fertilizer was 2.43%higher than that of whole grain amaranth for the utilization rate of N from grain amaranth in V9 and 2.11%higher in V12+10d.It could inhibit the absorption of N from grain amaranth for tobacco.The application of grain amaranth with a part of chemical fertilizer(A3)or whole chemical fertilizer(A4)could significantly increase the absorption of soil N in tobacco growing stage,and grain amaranth can be used as an alternative to nutrient N fertilizer in late growth stage. |
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