Verification of the effectiveness of fertilisation with digestates from biogas stations on yields of winter rape and winter wheat and changes in some agrochemical soil properties | Ověření účinnosti hnojení digestáty z bioplynových stanic na výnos ozimé řepky a ozimé pšenice a změny vybraných agrochemických vlastností půdy

In 2008 and 2009 in a small-plot field experiment (on soil with alow supply of K and Mg, sa tisfactory supply of P and Ca) we studied the effect of fertilising with two types of digestates, products from two biogas stations processing material of different raw material composition on the following: yield parameters of winter rape and winter wheat, changes in the content of mineral nitrogen (Nm.J in the soil, soil reaction (pH) and supply of available P, K, Mg and Ca in the soil. The digestates were applied in a single application and only in the spring of 2008 to a winter rape stand (stage of leaf rosette) at doses of 33.4 and 32.2 t per ha; that is 140 kg per ha N and 39 kg per ha P2O5, respectively. The dose of Kfi was 101 kg per ha (digestate I) and 39 kg per ha (digestate II). in the first experimental year after the application of the digestates the seed yields of winter rape increased significantly by 38.5 -57.7% (digestate I - II) in comparison to the unfertilised control; no statistically significant differences among the digestates were observed. Similar results were achieved also in the second experimental year; fertilisation with the two digestates increased the yields of winter wheat grain by 63.9% (digestate I) and 30% (digestate II), compared to the control. Significant differences were discovered between the two digestates. The Nmin content in the topsoil after the harvest of winter rape varied after fertilisation with the digestates and ranged between 11.9 and 19.9 mg per kg compared to 12.3 mg per kg in the control; after the harvest of winter wheat it ranged between 7.8 and 7.9 mg per kg compared to 14.9 mg per kg in the unfertilised control. After the application of the digestates the soil reaction (pH) and contents of available P, Mg and Ca in the soil did not change significantly. The application of digestate I containing considerably more potassium increased the supply of soil K significantly compared to the control and to fertilisation with digestate II.