In order to better utilize the last cut alfalfa harvested before killing frost in a high moisture environment, the effects of chemical additives on the quality of alfalfa silage were studied in south of China. The alfalfa was freshly harvested at branching stage, and wilted by dry matter content of about 300 g/kg (fresh matter basis). Silage was prepared by using a small-scale silage fermentation system, where sucrose, potassium citrate, sodium carbonate, formic acid, acetic acid and propionic acid were used as silage additives, and no additives served as control. These silos were stored at ambient temperature (5-20°C), and the silage qualities were analyzed after 120 days of fermentation. All additive treatments affected the chemical composition and N distribution, increased the water-soluble content and crude protein contents, decreased non-protein nitrogen (NPN) content, and enhanced the in vitro ruminal dry matter digestibility (except for sodium carbonate). Silages treated with organic acids were preserved with significantly (P < 0.05) lower pH value, ethanol content and NPN content compared with control. When the fermentation quality, chemical composition and N distribution were considered, the treatment with sucrose or organic acids resulted in high quality of alfalfa silage ensiled before killing frost, with formic acid having the best effect.

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Exchange reactions between Ca 2+

Effects of lactic acid bacteria (LAB) and formic acid (FA) on silage quality of ultraviolet (UV)-radiated Siberian wildrye (Elymus sibiricus L.) were studied on the Qinghai-Tibetan plateau. Siberian wildrye seeds were sown in early April, 2012 and harvested in 2013, 2014 and 2016. Fresh forage was radiated for 0, 4 and 8 h under ambient/laboratory UV radiation conditions during the wilting process, and then mixed with LAB inoculant (10 5 cfu g À1 fresh matter [FM]) and FA (3 mL kg À1 FM), respectively, no additives treatment as control. After additive treatments, chopped Siberian wildrye plants were packed in 30 cm 9 40 cm polythene bags and stored in a dark room at ambient temperature (<15°C) for 90 days. Silages of UV-radiated Siberian wildrye had higher (P < 0.05) pH and ammonia-nitrogen (N) content, lower (P < 0.05) acetic and propionic acid content and in vitro ruminal dry matter digestibility. Compared with control, treatments with additives (especially for inoculant LAB) enhanced pH decline, increased (P > 0.05) acetic acid content, decreased (P < 0.05) butyric acid and ammonia-N content of silages of UV-radiated Siberian wildrye. It was concluded that the application of FA and inoculant LAB at ensiling could reduce the negative effects of extended UV radiation on the process of wilting.

Abstract. Grassland ecosystems play important roles in the global carbon cycle. The net primary productivity (NPP) of grassland ecosystems has become the hot spot of terrestrial ecosystems. To simulate grassland NPP in southern China, a new model using productivity coupled with hydrothermal factors (PCH) was built and validated based on data recorded from 2003 to 2014. The results show a logarithmic correlation between grassland NPP and mean annual temperature and a linear positive correlation between grassland NPP and mean annual precipitation in southern China, both highly significant relationships. There was a highly significant correlation between simulated and measured NPP (R 2 = 0.8027). Both RMSE and relative root mean square error (RRMSE) were relatively low, showing that the simulation results of the model were reliable. The NPP values in the study area had a decreasing trend from east to west and south to north. Mean NPP was 471.62 g C m −2 from 2003 to 2014. Additionally, the mean annual NPP of southern grassland presented a rising trend, increasing 3.49 g C m −2 yr −1 during the past 12 years. These results document performance and use of a new method to estimate the grassland NPP in southern China.