Agricultural management can affect soil chemistry, nutrient cycling and microbial properties, but the relationship among them is not well explored. Catch crops play an important role in decreasing nitrogen (N) leaching in the autumn, and thereby reduce undesirable environmental effects, improve soil physical and microbiological properties. We investigated the effect of catch crops and straw management on soil mineral nitrogen (N min ) and microbial activity on a clay loam Gleyic Cambisol (CMg). A two-factor experiment was set up: 1) catch crops (narrow-leafed lupin, mixture of narrow-leafed lupin and oats, white mustard and without catch crops), and 2) straw management methods (with and without). The total amount of bacteria and fungi, dehydrogenase and urease activity, and potential nitrification rate were assayed during two successive spring barley growing seasons. Also we determined N in the soil and soil leachate. Our experimental findings indicated that the N min dynamics in the soil and nitrate nitrogen (N-NO 3 ) leaching depended on the catch crops, the amount of decomposers and the weather conditions. Cultivation of post-harvest catch crops in a clay loam Cambisol reduced N min content by 50-62% at the 0-40 cm soil layer, stubble breaking in the autumn by 23-41%, compared with the soil where the stubble had not been broken and no catch crops had been grown. Also, cultivation of catch crops reduced nitrate (N-NO 3 ) concentration in the soil leachate by 32-62%. The biological variables differed among all treatments, especially among years. Higher counts of heterotrophic bacteria and fungi and greater enzymatic activity were recorded in the plots with catch crops. Higher nitrification activity was established in the plots without catch crops. The amount of cellulose degrading bacteria did not differ significantly between the treatments. Further research is needed to get a better insight into the processes of mineralization and immobilization of catch crops' residues and soil N min and N-NO 3 leaching in agricultural ecosystems.

Experiments were constructed to investigate e ects of pea [Pisum sativum L. (Partim)] and spring cereal intercrops on annual weed suppression and grain yield in an organic farming system. Pea, spring wheat (Triticum aestivum L. emend. Fiori et Paol.), barley (Hordeum vulgare L.), oat (Avena sativa L.), and triticale (× Triticosecale Wittm.) were sown as sole crops and as intercrops at a 50:50 proportion of grain legume and spring cereal seeds relative to sole crop rates. e density of wheat, oat, and triticale sole crops was signi cantly higher compared with intercrops with pea. All investigated intercrops were signi cantly denser than the sole pea crop. Low height was observed in pea and barley sole crops and intercrops. Mostly weed number and mass were not signi cantly di erent between sole cereal and intercrops. Crop density was more e ected by suppression than weed height. Where crops were sparser, increases in weed density and mass corresponded to a signi cant decline in grain yield. In the peacereal intercrop, where pea accounted for 20.3 to 35.2% of the total plant number, cereals exhibited the greatest weed suppression ability, productive stem number and height being the main factors responsible for this.

Reducing tillage intensity and increasing crop diversity by including perennial legumes is an agrotechnical practice that strongly affects the soil environment. Strip tillage may be beneficial in the forage legume–cereals intercropping system due to more efficient utilization of biological nitrogen. Field experiments were conducted on a clay loam Cambisol to determine the effect of forage legume–winter wheat strip tillage intercropping on soil nitrate nitrogen (N-NO3) content and cereal productivity in various sequences of rotation in organic production systems. Forage legumes (Medicago lupulina L., Trifolium repens L., T. alexandrinum L.) grown in pure and forage legume–winter wheat (Triticum aestivum L.) strip tillage intercrops were studied. Conventional deep inversion tillage was compared to strip tillage. Nitrogen supply to winter wheat was assessed by the change in soil nitrate nitrogen content (N-NO3) and total N accumulation in yield (grain and straw). Conventional tillage was found to significantly increase N-NO3 content while cultivating winter wheat after forage legumes in late autumn (0–30 cm layer), after growth resumption in spring (30–60 cm), and in autumn after harvesting (30–60 cm). Soil N-NO3 content did not differ significantly between winter wheat strip sown in perennial legumes or oat stubble. Winter wheat grain yields increased with increasing N-NO3 content in soil. The grain yield was not significantly different when comparing winter wheat–forage legume strip intercropping (without mulching) to strip sowing in oat stubble. In forage legume–winter wheat strip intercropping, N release from legumes was weak and did not meet wheat nitrogen requirements.

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