| In order to study the effects of different nitrogen forms and application rate on the production performance,nutritional quality,and soil of Bothriochloa ischaemum,the appropriate nitrogen forms and levels were screened out meanwhile increase the productivity and quality of forage grass and achieve sustainable development of the soil to provide scientific basis for the production of B.ischaemum.This experiment was cultivated at the pratacultural science experimental field of Shanxi Agricultural University from 2015 to 2017,taking Taihang B.ischaemum as the materials and using randomized block design.Three different nitrogen forms of urea(U),ammonium sulfate(AS)and calcium ammonium nitrate(CAN)with four nitrogen levels of N0(CK),N30,N60,N120,and N240 kg N/hm2 respectively were applied to the cultivated Taihang B.ischaemum in the field.By analyzing and comparing of yield,nutritional quality and grassland soil of B.ischaemum and a comprehensive evaluation using the gray correlation of its production performance and nutritional quality was conducted.The results showed that:1.By measuring the yield,crude protein(CP),neutral detergent fiber(NDF),acidic detergent fiber(ADF),crude fat(EE),crude ash(Ash),calcium(Ca),phosphorus(P)content of B.ischaemum,comprehensive evaluation using gray correlation analysis of the production performance and nutritional quality.It can be seen that when urea(U)is applied to B.ischaemum,the production performance and nutritional quality of U60 are the best;when ammonium sulfate(AS)is used,AS60 is the best;when calcium ammonium nitrate(CAN)is used,CAN120 is the best.The mean values of the three nitrogen forms indicators were higher in urea,but the difference was not significant.2.The effects of different nitrogen forms and application rate on the contents of soil organic matter,nitrate nitrogen,ammonium nitrogen,available phosphorus and potassium were different in the short-term application of B.ischaemum.The contents of organic matter in the experiment were the highest in CAN120,followed by U120,AS240.The content of available phosphorus and available potassium in the 0-10 cm soil layer are generally larger than 10-20 cm,especially for the available potassium,and it has no significant difference of the content of available phosphorus and potassium in each 10-20 cm.In 0-10 cm soil layer,the content of nitrate nitrogen was the highest in U120(15.38 mg/kg),which was significantly higher than that in the control group(18.31%),but there was no significant difference between AS and CAN.The ammonium nitrogen content in the 0-10 cm soil layer was not significant under various nitrogen forms and application rates,but there was a significant difference in the 10-20 cm soil layer(P<0.05),with the highest AS120 content(15.78 mg/kg).),followed by Ueo,CAN120.3.When short-term application of different nitrogen forms and application rate,the changes of soil enzyme activity in the grass of B.ischaemum were less.The activity of soil invertase was only in the 10-20 cm soil layer.There was a significant difference in activity between the three forms nitrogen forms and application rate.The activity of soil sucrase was the highest in U60,followed by AS30 and CAN30.In the 0-10 cm and 10-20 cm soil layers,the activities of invertase and catalase in soil were all three nitrogen forms was maximum;all three forms of nitrogen had higher alkaline phosphatase activities with U60,AS30,and CAN30,respectively.Soil urease activity was highest with U240(6.00 mg NH3-N/g),which was significantly higher than that of nitrogen application,which was 62.16%higher than that of the control group.and applying U could promotes urease activity. |
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