SUMMARYThe impact of liquid cattle (Bos taurusL.) manure, applied to soil at common rates and for several years, on certain plant parameters and soil properties has not been studied extensively. The objectives of this study were: a) to assess the effects of manure application on corn (Zea maysL.) yield, macro- and micronutrient concentrations and uptake, in a three-year (2006–2008) field experiment conducted in northern Greece and b) to evaluate the 11-year effect of manure application on soil fertility (particularly on micronutrients avialability) and chemical properties (especially on organic C and total N content). The field experiment of this study had been used in a similar fertilisation experiment since 1996. The treatments, which were applied on the same plots each year over the 11-year period, were: (i) soil incorporation of liquid dairy cattle manure before sowing, at a rate equal to the common N-P inorganic fertilisation for each crop (based on manure's total N and P content); (ii) application of the common inorganic N-P fertilisation for each crop before sowing; (iii) identical to ii, but with split application of the N fertilisers; (iv) no fertilisation (control). Corn dry aboveground biomass yield at the R3 growth stage and grain yield, N, P, K concentrations and macro- and micronutrients uptake increased (p≤ 0.05) upon manure addition at levels similar to or higher than the inorganic fertilisation treatments. The relative increase in grain yield during the three-year period ranged between 63–75% for manure treatment and 50–75% for both inorganic fertilisation treatments. After 11 years of manure application, organic C, total N, and available NO3-N, P, K, Cu, Zn, Mn, and B increased (p≤ 0.05) in the surface soil (0–30 cm). However, no trend of nutrient build up was evident through years (except for Zn). Surprisingly, salinity and available NO3-N in the 60–90 cm soil depth of the manure-treated plots were lower (p≤ 0.05) than that of the inorganic fertilisation treatments and similar to control. Electrical conductivity was 1.76, 3.05, 2.96 and 1.36 dS m−1, for manure treatment, the two inorganic fertilisation treatments and control, respectively, whereas the respective NO3-N concentrations were 7.7, 44.6, 55.1 and 8.3 mg kg−1. Conclusively, repeated application of liquid cattle manure into the soil, at rates comparable to the common inorganic fertilisation for 11 years, can enhance crop yield and macronutrient concentrations in plant tissues and uptake, at levels similar to the inorganic fertilisation. In addition, it can increase micronutrients plant uptake and maintain soil fertility with respect to both macro- and micronutrients and increase soil organic C and total N, without either causing nutrient build up or increasing soil salinity and NO3−accumulation in the deeper soil layers.
Results of researching the process of treatment of cattle manure in a vortex layer apparatus
