Effect of Farming System and Irrigation on Physico-Chemical and Biological Properties of Soil Under Spring Wheat Crops

A field experiment in growing spring wheat (Triticum aestivum L. - cv. ‘Monsun’) under organic, integrated and conventional farming systems was conducted over the period of 2020–2022 at the Czesławice Experimental Farm (Lubelskie Voivodeship, Poland). The first experimental factor analyzed was the farming systems, which included: A. organic system (control) - without the use of chemical plant protection products and mineral fertilization NPK; B. conventional system - the use of plant protection products and NPK fertilization in the range and doses recommended for spring wheat; C. integrated system - use of plant protection products and NPK fertilization in an "economical" way - doses reduced by 50%. The experimental factor was irrigation strategy of spring wheat crops: 1. no irrigation - control; 2. double irrigation (at the beginning of crop vegetation and in the phase of critical water demand of wheat; 3. multiple irrigation resulting from the monitoring of drought in the agricultural field. The aim of the research was to determine the physical, chemical and enzymatic properties of loess soil under spring wheat crops as influenced by the factors listed above. The highest organic C content of the soil (1.11%) was determined in the integrated system with multiple irrigation of spring wheat, whereas the lowest one (0.77%) - in the conventional system without irrigation. In the conventional system, the highest contents of total N (0.15%), P (131.4 mg kg-1), and K (269.6 mg kg-1) in the soil were determined under conditions of multiple irrigation. In turn, the organic system facilitated the highest contents of Mg, B, Cu, Mn, and Zn in the soil, especially upon multiple irrigation of crops. It had also the most beneficial effect on the evaluated physical parameters of the soil. In each farming system, the multiple irrigation of spring wheat significantly increased moisture content, density and compaction of the soil and also improved its total sorption capacity (particularly in the integrated system). The highest count of beneficial fungi, the lowest population number of pathogenic fungi, and the highest count of actinobacteria were recorded in the soil from the organic system. Activity of soil enzymes was the highest in the integrated system, followed by organic system - particularly upon multiple irrigation of crops. Summing up, the present study results demonstrate varied effects of the farming systems on the quality and health of loess soil; however, the integrated system was proved to ensure its most stable and equalized physicochemical and biological parameters. The multiple irrigation of crops resulting from indications of soil moisture sensors mounted on plots (indicating the real need for irrigation) contributed to the improvement of almost all analyzed soil quality indices.