Analysis of Grassland Productivity and Carrying Capacity of Natural Warm-temperature Tussock in the Central Region of Guizhou Province

[Objective] This study aimed to investigate the influences of grazing and fencing on grassland productivity and carrying capacity of subtropical natural warmtemperature tussock. [Method] With the natural warm temperature tussock in Longli County of Guizhou Province as study area, monthly, seasonal and annual dynamics of grassland productivity were investigate continuously during 2010 -2012, and the data were analyzed. [Result] Under grazing and fencing conditions, grassland present biomass and forage growth of warm temperature tussock in Longli County of Guizhou Province both increased first and decreased, reaching the maximum from August to October. Fencing significantly improved the productivity of natural grassland but had little effect on the vegetation composition. [Conclusion] From the perspective of grass-livestock balance, the suitable stocking capacity of warm-temperature tussock in the central region of Guizhou Province was 3.45 -4.66 sheep/hm2 , which has high ecological efficiency and can be borne by farmers and herdsmen.

Sheep manure application increases soil exchangeable base cations in a semi-arid steppe of Inner Mongolia

The long-term productivity of a soil is greatly influenced by cation exchange capacity（CEC）.Moreover,interactions between dominant base cations and other nutrients are important for the health and stability of grassland ecosystems.Soil exchangeable base cations and cation ratios were examined in a 11-year experiment with sheep manure application rates 0–1,500 g/（m2？a） in a semi-arid steppe in Inner Mongolia of China,aiming to clarify the relationships of base cations with soil p H,buffer capacity and fertility.Results showed that CEC and contents of exchangeable calcium（Ca2＋）,magnesium（Mg2＋）,potassium（K＋） and sodium（Na＋） were significantly increased,and Ca2＋ saturation tended to decrease,while K＋ saturation tended to increase with the increases of sheep manure application rates.The Ca2＋/Mg2＋ and Ca2＋/K＋ ratios decreased,while Mg2＋,K＋ and Na＋ saturations increased with increasing manure application rates.Both base cations and CEC were significantly and positively correlated with soil organic carbon（SOC） and soil p H.The increases of SOC and soil p H would be the dominant factors that contribute to the increase of cations in soil.On a comparison with the initial soil p H before the experiment,we deduced that sheep manure application could partly buffer soil p H decrease potentially induced by atmospheric deposition of nitrogen and sulfur.Our results indicate that sheep manure application is beneficial to the maintenance of base cations and the buffering of soil acidification,and therefore can improve soil fertility in the semi-arid steppes of northeastern China.