Studies On Moisture Content Measurement Method And Forage Moisture Contents Under Different Situations

Moisture content is one of the most important indexes for determining forage harvesting time, estimating yield, evaluating forage quality and safe guiding storage of forage. This research compared different moisture measurement methods in their accuracies and investigated forage moisture contents of different plant species under various situations in terms of vegetation types, yearly and seasonal fluctuations. Environmental factors affecting moisture content measurements were also studied. The main research results were as follows:(1) The results showed that there were some discrepancies between the oven-drying method and the ambient air-drying method for different plants. The moisture content measured by ambient air-drying method was about 10% higher than that measured by oven-drying method. High-temperature oven-drying method for fast killing plant living tissue materials showed no significant differences with the conventional low-temperature drying method. The Proportional relationship between measurements by different methods was established, which can be used to justify the moisture content measurement made with ambient air-drying method under field conditions.(2) Plant moisture contents varied with different plant families. Drying speeds in terms of reaching constant plant dry weight in different plants varied. Legume plants need the least time of only 4 days for drying, while the mixture of various plants took a much longer period of 8 days for drying.(3) Ratios of plant dry weight to fresh weight were determined for different grassland types. The results showed variations existed among different grassland types, as well as among different plant communities within the same grassland category. In particular, different plant communities under grassland types of arid grassland and herbosa grassland showed great variations in dry/fresh weight ratio. No reliable prediction can be drawn using grassland types as references for estimating forage moisture contents. It was suggested that more accurate estimations should be made through carefully examining the plant compositions for moisture content determination.(4) Ratios of plant dry weight to fresh weight increased gradually from early May to early September. The ratio in late September was significantly higher than the ratio in mid June. Based on parameters obtained from this research, methods for quick estimating dry-weight/fresh weight ratios for typical grassland were proposed.(5) External environment factor of wind speed was an important factor affecting the determination of forage moisture content. Wind velocity was also an important factor for forage drying. Rains in late July to mid-August had great influence for forage drying.