The utilization of results from long-term field trials aimed to study of phosphoric regime of fertile soils | Využití výsledků z dlouhodobých pokusů ke studiu fosforečného režimu úrodných půd
2012
Macháček, V., Výzkumný ústav rostlinné výroby, Praha 6 - Ruzyně (Czech Republic) | Lipavský, J.
On the basis of results from part of long-term field experiments evaluation of phosphorus regime in fertile soils and mostly used methods for determination of available phosphorus (Egners, Olsens and Mehlich 3 method) was done by the help of forms of soil phosphorus (labile P - P sub(lab) and mobile - P sub (mob) and kinetic indicators (sorption index, rate of releasable labile phoshorus and sorption-desorption curves) implementation. P sub(lab) and Olsens method show the highest correlation coefficients with uptake P by plants and that is why are most suitable indicators for determination of plant nutrition phosphorus. In fertile soils method according to Mehlich 3 is more suitable for determination of plant nutrition by phosphorus than Egners method. Egners method preferably reacts on raising content of soil phosphorus aňer P-fertilizers doses and it is because it releases from soil P sub(lab) and P sub(mob). The least reaction on raising content of phosphorus in soil showed Olsens method and it was because it released from soil largely P sub(lab). The optimal range of content of phosphorus in soil for Olsens method and Plab was identified (Olsens method: HN and CEm 35-50 mg per kg P; P sub(lab) for HN 29-40 mg per kg P and for CEm 22-33 mg per kg P). The three variants of P fertilization were used for resource of plant nutrition, that are issued from current data related to economical situation: optimal range - economic fertilization of 16 kg per ha P; at smaller content than optimal range - intensive fertilization of 22 kg per ha P and at larger content than optimal range - minimum fertilization of 8 kg per ha P. Doses of P-fertilizers wouldnt have get to below determinate values. For practical utilization determination of P sub(lab) and sorption index are sufficient. Other kinetic indicators are useful only for research purposes.
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