Agrocenosis Stability during Long-Term Application of Fertilizers on Soddy-Podzolic Soil

Abstract

In a long-term field experiment in the western part of the nonchernozemic zone of Russia (Smolensk oblast) on sandy loamy soddy-podzolic soil (Albic Glossic Retisol (Loamic)), the comparison of the effect of various rates and combinations of organic and mineral fertilizers revealed their efficiency in all the studied variants, except for the separate application of phosphorus fertilizers. It was found that the organomineral system—N90P90K90 + manure 9 t/ha—provided a deficit-free humus balance in the soil and stable productivity of crops (average for 30 years) at the level of 3.79 tons of forage units per hectare, or 37% higher than the control (without fertilizers). The mineral fertilizer system—N90P90K90—by the end of the fourth crop rotation was not inferior in the productivity to the organomineral system, but it led to a decrease in the soil humus content and pHKCl. The organic system with an annual manure rate of 9 t/ha occupied an intermediate position with respect to the crop rotation productivity (3.41 t/ha of forage units), as well as with respect to the soil fertility reproduction. A reliable increase in crop yield in the aftereffect was only recorded in the variants of organic and organomineral fertilizer systems, i.e., when soils were saturated with organic matter from manure. The soil in these variants was characterized by the high total number of microorganisms.