Evaluating Dairy Manure as Initial Fertility Driver for Mudflat Soil Amendment

The mudflats along the East Coast of China can be important alternative sources for arable lands if amended by large amount of organic fertilizers. Rich in organic matter and other nutrients, dairy manure has been considered as the economic choice for an initial fertility driver. Therefore, the goal of this study was to evaluate the impact of dairy manure amendment (DMA) as an initial fertility driver at application rates of 0, 30, 75, 150, and 300 t ha–1 on soil physicochemical properties, biomass and growth of ryegrass (Lolium perenne L.) grown in mudflat soil. The results showed that the DMA decreased soil bulk density in comparison to the unamended soil. The organic matter (OM) content in mudflat soil increased with increasing DMA rates. The salinity of mudflat soil decreased with increasing DMA rates, and the salinity at 30, 75, 150 and 300 t ha–1 DMA rates, corresponded to decreases of 26.1%, 35.8%, 37.8% and 45.4%, compared to 8.63 g kg–1 in the unamended soil. Electric conductivity (EC) of mudflat soil decreased with increasing DMA rate, while cation exchange capacity (CEC) increased duo to DMA. The contents of total N, total P, alkaline N, and available P in mudflat soil increased with increasing DMA rates. The increment of green herbage yield of ryegrass at 210 DAS at 30, 75, 150, and 300 t ha–1 DMA rates were 257.7%, 303.5%, 414.8%, and 516.6%, compared to the unamended soil (p < 0.05). Soil total Cu and Zn increased while total Mn, Ni, and Cr remained unchanged in response to DMA due to the high Cu and Zn content in the dairy manure. However, The DMA increased most of available metals except for Ni. In summary, land application of dairy manure as initial fertility driver could be an effective and safe way to amend mudflat soil, due to the rapid development of soil initial fertility, which enhanced green manure ryegrass (Lolium perenne L.) growth.