Browsing by Author "Mustonen, Arja"

In Finland 90% of all farmers and 95% of cultivated land are committed to the environmental support program of agriculture. One of the goals of this program is to reduce phosphorus (P) runoff from fields to the water system by limiting the amount of P used in cultivation process. Experiments on P rates allowed in environmental support program and practices of P fertilization were conducted at two sites on ley during 2003-2011. The research aimed to define the effects of annual fertilization, incorporated fertilization and the use of liquid manures on ley yield and P status of the soil. Earlier studies have shown that more water soluble P runs off from leys than from cereal fields and that reserved P hasn’t been sufficient for the whole ley rotation. The experiment consisted of seven different fertilization treatments in which phosphorus treatments were done as incorporate fertilization or annual fertilization. Low or high-release mineral fertilizer was used for incorporate fertilization and either mineral fertilizer or at first mineral fertilizer and liquid manures in next rotation for annual fertilization on the surface. P given as liquid manure was used by three members of the experiment group. The experiment included cultivating ley for seven years and cereal forage for two years. The control group used no P fertilization. P given in fertilization treatments had no effect on ley yields compared with control treatment. Negative P balance in all treatments caused the P rate in ploughed layer of the soil to decrease, however the P levels of surface layer fluctuated greatly regardless of the way P treatments were done. The study indicated that using liquid manures for fertilizing ley cultivations does not pose any greater threat to the environment than mineral fertilizers. However, balanced fertilization, sufficient nitrogen and reducing nitrogen loss of liquid manures are required in order to achieve high yields. The results also indicate that it should be made possible to raise the amount of P fertilization of highly productive leys closer to the zero level of the nutrient balance so that productivity of the soil measured by acid ammonium acetate (PAC) would be preserved. Depending on the other qualities of the soil, this can be done when PAC has reached the value nearby 10 mg l-1. More information on controlling P of the surface soil by means of cultivation management is needed.