Acid and alkaline phosphatase activities of agricultural land.

Agricultural soil contains phosphatases in variable amounts depending on microbial count, amount of organic materials, other macroscopic living organisms and their activities. The amount of phosphate released into the soil can then be directly co-related to soil fertility. The Agricultural Research and Development Station in Oradea (Bihor county) provided opportunity to study the effects of 18 years of cultivation on preluvosoil. The objective of the work reported was to determine at this site the effects of soil management practices on phosphatase activities as an index of soil biology. Phosphatase (phosphomonoesterase) activities were determined in the 0–20-, 20–40and 40– 60cm layers of a preluvosoil submitted to a complex tillage (no-till and conventional tillage), crop rotation (2and 6crop rotations) and fertilization [mineral (NP) fertilization and farmyardmanuring] experiment. Each activity decreased with increasing sampling depth. No-till – in comparison with conventional tillage – resulted in significantly higher soil phosphatase activities in the 0–20and in significantly lower activities in the deeper layers. The soil under maize or wheat was more enzyme-active in the 6than in the 2crop rotation. In the 2 crop rotation, higher phosphatase activities were recorded under wheat than under maize. Farmyard-manuring of maize in comparison with mineral (NP) fertilization – led to a significant increase in each activity. Maintenance of enzyme activities over tens of years in agricultural soils is partly attributed to traditional management practices including rotations with legumes, additions of animal manures, and minimum tillage. The phosphatases present in a soil sample are heterogeneous and might be utilized as a major parameter to assess soil fertility in an agricultural land.