| The amount of nitrogen fertilizer usage is huge in our country,which lead to soil harden and crop uptake efficiency is low,fertilizer loss serious,then,it causing the eutrophication and pollution of groundwater,and the ecological environment was serious damaged.The Leguminous forage grass as a green manure,which plays an important role in improving soil fertility,especially in improving soil nitrogen nutrition.Previous researches focused on the Effects of soybean crop and field green manure on soil physical and chemical properties.But the study of the effects of Mountain Chamaecrista on improving soil fertility and soil soluble nitrogen and the enzyme activity is less.This paper carry out the effects of fertilization application on agronomic traits of two Chamaecrista spp(Chamaecrista rotundifolia and Chamaecrasta nictitans)and soil soluble nitrogen,which can provide scientific basis and practical guidance for designing for high quality cultivation of C.rotundifolia and C.nictitans in hilly red soil region of southern china and reducing the application amount of nitrogen fertilizer.The main results are as follows:(1)Nitrogen,phosphorus and potassium fertilizer could improve in different degrees of C.rotundifolia and C.nictitans plant height,root length,pod number,nodule number,fresh weight,root nitrogen content,nitrogen content of stem,leaf nitrogen content,pod nitrogen content and soil total nitrogen,but it had no significant effect on soil pH(P>0.05).(2)In the condition of applying nitrogen fertilizer,the soil TSN,ammonium nitrogen,nitrate nitrogen and SON content by planting C.rotundifolia were higher in flowering and fruiting period,branching period and wither period is lower.The 4 kinds of nitrogen content of soil by planting C.nictitans flowering period were higher and branching period is lower.Among the nitrogen treatments,the content of 4 kinds of nitrogen in the soil of C.rotundifolia increased with the increasing of nitrogen fertilizer amount in seedling period and branching stage,and it showed a downward trend after the first increase with the increase of nitrogen fertilizer amount in flowering,podding stage and withering period.Compared with N1,nitrogen fertilizer could improve significantly the soil ammonium nitrogen and nitrate nitrogen content in the flowering and podding stage(P<0.05),but it did not increased significantly in withering period(P>0.05).the content of 4 kinds of nitrogen in the soil of C.nictitans increased with the increasing of nitrogen fertilizer amount in seedling period and branching stage,the content of soil TSN and nitrate nitrogen disincreased with the increasing of nitrogen fertilizer amount in flowering and podding stage and withering period,while soil ammonium nitrogen showed a downward trend after the first increase with the increase of nitrogen fertilizer amount.Compared with N1,nitrogen fertilizer could improve significantly the soil ammonium nitrogen content in the flowering and podding stage(P<0.05),but it did not increase significantly in withering period(P>0.05).(3)In the condition of applying nitrogen fertilizer,The 4 enzyme activities of soil by planting C.rotundifolia were higher in flowering and fruiting period,other times its activity due to different enzyme species;The 4 enzyme activities of soil by planting C.nictitans were different due to different enzyme species;Among nitrogen treatments,The 4 enzyme activities of soil by planting C.rotundifolia showed a downward trend after the first increase with the increase of nitrogen fertilizer amount in all times.Compared with N1,nitrogen fertilizer could improve significantly the protease activity in all times(P<0.05),but it did not improve significantly the urease activity(P>0.05).nitrogen fertilizer could improve significantly the L-asparaginase activity of soil by planting C.rotundifolia and C.nictitans in seedling period and flowering period(P<0.05),while it did not improve significantly in other times(P>0.05).nitrogen fertilizer could improve significantly the Transglutaminase activity of soil by planting C.rotundifolia and C.nictitans in podding period(P<0.05),while it did not improve significantly in other times(P>0.05).(4)In the condition of applying phosphate fertilizer,the soil TSN,ammonium nitrogen,nitrate nitrogen and SON content by planting C.rotundifolia and C.nictitans were higher in flowering and podding period.Among the phosphate treatments,the content of 4 kinds of nitrogen in the soil of C.rotundifolia and C.nictitans increased with the increasing of phosphate fertilizer amount in seedling period,Compared with P1,P5 could increase significantly the content of 4 kinds of nitrogen(P<0.05);phosphate fertilizer could improve significantly the TSN content of soil by planting C.rotundifolia in the flowering,podding stage and withering period(P<0.05),while the TSN content of soil by planting C.nictitans was inhibited(flowering period)or not significantly increased(podding period)by high phosphate fertilizer(P5).The ammonium nitrogen content of soil by planting C.rotundifolia and C.nictitans showed a downward trend after the first increase with the increase of phosphate fertilizer amount in flowering and podding stage and withering period,phosphate fertilizer could improve significantly the soil ammonium nitrogen content in podding stage and withering period(P<0.05),but it did not increase significantly in flowering period(P>0.05).phosphate fertilizer could improve significantly the content of soil nitrate nitrogen and SON(P<0.05),however,the appropriate amount of phosphorus has yet to be studied.(5)In the condition of applying phosphate fertilizer,The 4 enzyme activities of soil by planting C.rotundifolia and C.nictitans were higher in flowering and podding period,other times its activity due to different enzyme species.Among the phosphate treatments,there was no significant difference in urease activity of soil by planting C.rotundifolia and C.nictitans in all periods(P>0.05);The Soil protease activity of soil by planting C.rotundifolia and C.nictitans showed a downward trend after the first increase with the increase of phosphate fertilizer amount in all period.Compared with P1,phosphate fertilizer could increase significantly the protease activity of Soil by planting C.rotundifolia and C.nictitans(P<0.05),but it did not increase significantly in other periods(P>0.05);phosphate fertilizer is no no significantly effect on the L-asparaginase activity of Soil by planting C.rotundifolia.Compared with P1,phosphate fertilizer is no no significantly effect on the L-asparaginase activity of Soil by planting C.nictitans at the seedling stage,the flowering and fruiting period(P<0.05);phosphate fertilizer could improve significantly the transglutaminase activity of Soil by planting C.rotundifolia in the seedling stage,branching stage and flowering stage,phosphate fertilizer could improve significantly the transglutaminase activity of Soil by planting C.nictitans in the seedling stage.(6)In the condition of applying potash fertilizer,two species of soil TSN and SON content reached the peak in the flowering stage,the content of ammonium nitrogen in soil is higher in seedling and flowering stage,branching period is low,the content of nitrate in soil did not change significantly in different periods.Among the potash fertilizer treatments.Compared with Kl,potash fertilizer could not improve significantly the TSN,ammonium nitrogen,nitrate nitrogen and SON content of Soil by planting C.rotundifolia and C.nictitans in the seedling stage,and branching stage(P>0.05),and then,potash fertilizer could improve significantly this 4 soil nitrogen content(P<0.05).(7)In the condition of applying potash fertilizer,The 4 enzyme activities of soil by planting C.rotundifolia and C.nictitans were higher in flowering,other times its activity due to different enzyme species.Among the potash fertilizer,treatments,there was no significant difference in urease activity of soil by planting C.rotundifolia and C.nictitans in all periods(P>0.05);Compared with Kl,potash fertilizer could improve significantly the protease activity of Soil by planting C.rotundifolia and C.nictitans in the branching stage,flowering stage and podding stage(P<0.05);There was no significant difference in L-asparaginase activity of soil by planting C.rotundifolia in all periods(P>0.05);Compared with Kl,potash fertilizer could improve significantly the L-asparaginase activity of Soil by planting C.nictitans in the flowering stage and podding stage(P<0.05);Compared with K1,potash fertilizer could improve significantly the Transglutaminase activity of Soil by planting C.rotundifolia in the seedling stage(P<0.05);Compared with K1,potash fertilizer could improve significantly the Transglutaminase activity of Soil by planting C.nictitans in Branching and flowering stage(P<0.05). |
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