Long-term experiments with fertilizers-essential fertility changes

Abstract

The paper presents soil analytical data and their interpretation from samples in long-term experiments as a result of NP, NPK and organo-mineral fertiliser applications in a stationary system for 20 years and wheat-maize-soybean rotation system. The results show that NP fertilisation (from ammonium nitrate and superphosphate) leads to acidification of soils (regardless of soil type) depending on increasing N a.i./ha. The acidification phenomenon is higher in typical preluvosol (taxonomically acidic soil) due to activation of adsorbed (potential) acidity and solubilisation of Al ions, with devolatilisation of adsorbent complex, which updates for this soil the need for correction of the reaction (pH) by means of calcium amendments. In contrast, for the alluvial mollisol, with neutral - weakly alkaline pH and higher humus % and high buffering capacity, the multiannual acidification due to N is reduced. NP, NPK mineral fertilisation, in balanced doses, can maintain the organic-C and humus content constant, balanced, within the specific limits of the soil type over a period of 20 years, with wheat-maize-soybean crop rotation. In contrast, amendment and processing conventional intensive tillage (on maize) decrease the content of these indicators, a phenomenon that can be attributed to the enhanced mineralisation of the soil organic component. Organic and organo-mineral fertilisation can lead to a favourable modelling of humus content. The mobile forms of the essential elements of nutrition and fertilisation (N, P, K) are improved in terms of their bioavailability with the objective that these forms will maintain their quantity and quality at the level required by crops and their supply by fertilisation technologies is ensured rationally and preventively for the soil-plant system. In summary, the analytical results from long-term experiments with fertilisers are of direct benefit to soils, their productivity and fertility, with the implementation of sustainability principles.