2013 Volume 56 Issue 2 Pages 143-150
Since Kyushu is the base of beef cattle industry in Japan, livestock wastes needs to be treated effectively as an organic fertilizer replacing inorganic or chemical fertilizers in forage production. However, little is known about the differences in mineralization characteristics and fertilizing efficiency between farmyard manures derived from cattle with different feeding systems. Thus, effects of farmyard manures derived from fattening beef cattle with co-digestion substrates of sawdust (abbreviated as F+SM) and breeding beef cattle under the feeding of sawdust (B+SM) or grazing on bahiagrass with the substrate of sawdust (B+BSM) or rhodesgrass (B+BRM) were examined for herbage yield, nitrogen content and soil chemical properties in tropical colored guineagrass. Even though the F+SM had lowest total nitrogen (TN) content with highest carbon/nitrogen (C/N) ratio, herbage dry matter yield (DMY), crude protein (CP) content and chlorophyll content in colored guineagrass were highest in the F+SM, on the contrary to the B+BRM which had highest TN content with lowest C/N ratio, leading to the lowest herbage DMY and CP content. Nitrogen mineralization characteristics of farmyard manure determined by an incubation method showed the highest efficiency from F+SM, followed by B+BSM, B+SM and lowest from B+BRM, which lead to an resolution for the contradiction between chemical properties of farmyard manure and the grass growth. Soil chemical properties such as pH and TN content did not vary so much and were hardly correlated with these herbage yield and TN content. It is proposed that the characteristics and fertilizing efficiency of beef cattle farmyard manures should be variable depending on beef cattle feeding systems and co-digestion substrates, and the F+SM had highest fertilizing efficiency on the grass growth among farmyard manures examined.