| Effect of alfalfa growth years on its yield and soil characteristics |
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| DOI：10.7606/j.issn.1000-7601.2008.03.21 |
| Key Words: alfalfa number of growth years yield characteristics of soil |
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| Abstract: |
| By method of field investigation the yield of alfalfa with different growth ages from 3～26 years was determined and the soil samples from 0～20，20～40，40～60cm and80～100cm layers were collected to analyze the variation of soil moisture volumetric weight and organic matter．The results indicated that the yield of dried alfalfa increased and then declined with alfalfa growth ages increasing．The yield of 6-year alfalfa was the highest reaching9738kg／hm2．In each of layers greater variation amplitude was in water content of soil with 3 to 12－year alfalfa ranging within 7．90％～17．46％ and the variation mainly occurred at 80～100 cm soil layer．For soil with more than12－year alfalfa the variation amplitude in water content ranging 7．24％～12．66％ was smooth．The layer of soil volumetric weight in decreasing order was 20～40＞40～60＞0～20 cm．The soil volumetric weight of 80～100 cm soil layer was smooth．The soil organic matter content with 3－year alfalfa was the lowest of those years．The soil organic matter content of the order layer was 1．59, 1．82, 2．42 g／kg and 2．08 g／kg．The soil organic matter content of soil with alfalfa growth ages increasing from 4 years to 18 years at each of soil layers variation amplitude ranging within 10．41～12．75,8．02～9．73,6．49～10．09 g／kg and 7．74～12．58 g／kg respectively．The organic matter content began to rise for soil with more than 18－year alfalfa and the variation amplitude was 2．69,1．39,1．37g／kg and 0．97g／kg in each layer of the soil respectively．The study indicated that alfalfa showed a trend of degradation the soil water volumetric weight and organic matter indicated the trend of decline with alfalfa growth ages increasing. |