Effect of liquid cattle manure on corn yield, composition, and soil properties

The effects of liquid dairy cattle (Bos taurus) manure on corn (Zea mays L.) yield and composition were studied in a 4-yr field experiment conducted under a Mediterranean environment. In addition, long-term impact of (8-yr) manure application on soil-available NO3-N, P, and K; organic C; Kjeldahl N; and salinity was investigated. Four treatments were established in plots, previously used for a similar 4-yr experiment with winter wheat (Triticum aestivum L.). Treatments were: (i) application of 80 Mg manure ha(-1) yr(-1); (ii) single application of the equivalent N-P as inorganic fertilization (260 kg N ha(-1) yr(-1) and 57 kg P ha(-1) yr(-1)); (iii) identical to (ii), but with split N application; and (iv) no fertilization. Corn grain and silage yields, N-P-K plant concentration, and uptake were significantly increased by manure or inorganic fertilizer addition relative to the control. During the 4-yr corn experiment, the amounts of available NO3-N in the soil profile of manure plots were higher than control, but similar to both inorganic fertilization treatments. Manure application maintained the amounts of soil available NO3-N, P, and K at desirable levels, almost each year of the total 8-yr application. However, soil organic C and Kjeldahl N remained unchanged. At the end of the experiment, soil salinity below 30 cin was significantly increased on manure or inorganic fertilizer addition relative to the control, but at levels acceptable for most crops. In conclusion, soil application of liquid dairy cattle manure at a rate equivalent to the recommended inorganic fertilization can enhance corn yield and composition and maintain soil fertility at desirable levels, without increasing soil salinity at unacceptable levels.