| Exploitation and utilization of summer fallow farmland on main river valley areas in Tibet |
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| DOI：10.7606/j.issn.1000-7601.2008.04.21 |
| Key Words: Tibet river valley area summer fallow farmland thermal and water resources |
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| Abstract: |
| According to the present situation of agricultural resources and summer fallow land on mainriver valley areas in Tibet it is climatically possible for summer fallow land to implement perennial cropping system in thermal and moisture conditions using perennial accumulated temperature and rainfall in ten days．Lhasa and Lhoka regions locate in main field in middle river valley areas of Tibet．The analytical results show：As for the 86 types of perennial cropping patterns in winter wheat areas the range of accumulated temperature is from 2000℃ to 4750℃ mean accumulated temperature is 3475．1℃．The change of rainfall in this region is from 456 to 744 mm average rainfall is 636 mm While there are23patterns in winter and spring wheat mixed planting areas their range of accumulated temperature is from 2050℃ to 3850℃ mean accumulated temperature is 2778．7℃．The change of rainfall is from446to580mm the average rainfall is528mm．Results in the field experiments of this areas for summer fallow farmland in2006showed that the optimum cropping ratio of winter wheat intercropping common vetch in Lhasa was66％ to33％；spring barley intercropping maize was an optimum cropping patterns in spring barley intercropping maize potato and common vetch in Lhasa and Shannan． But spring barley intercropping common vetch had higher economic value in three cropping patterns in Shannan region．Forage yield of sole cropping is higher than intercropping with grain． |