Nitrogen migration in crop rotations differing in fertilisation

Inappropriate use of nitrogen fertilisers is becoming a global problem; however, continuous fertilisation with N fertiliser ensures large and constant harvests. To evaluate the relationships of differently fertilised cultivated plant rotation with N metabolism in the agroecosystem the research was conducted between 2006 and 2013 at Lipliūnai, Lithuania, in fields with calcareous gley brown soil, i.e. Endocalcari Endohypogleyic Cambisol (CMg-n-w-can). The research area covered three drained plots where crop rotation of differently fertilised cereals and perennial grasses were applied. The greatest productivity was found in a higher fertilisation (TII, 843 kg N/ha) cereals crop rotation. With less fertilisation (TI, 540 kg N/ha) crop rotation productivity of cereals and perennial grasses (TIII, 218 kg N/ha) was 11-35% lower. The highest amount of mineral soil N (average 76 kg/ha) was found in TI. It was influenced by fertilisation (r=0.71) and crop productivity (r=0.39). TIII tended to reduce Nmin (12.1 mg/L) and Ntotal (12.8 mg/L) concentrations in drainage water and leaching of these elements (7 and 8 kg/ha). Nmin and Ntotal concentrations in the water depended on crop productivity respectively (r=0.48; r=0.36), quantity of mineral soil N (r=0.65; r=0.59), fertilisation (r=0.59; r=0.52), and N balance (r=0.26; r=0.35). Cereal crop rotation increased N leaching by 12-42%. The use of all crop rotations resulted in a negative N balance. Nitrogen balance depended on fertilisation with N fertiliser (r=0.55). The application of perennial grasses crop rotation in agricultural fields was the best environmental tool, reducing N migration to drainage

Drainage runoff and migration of mineral elements in organic and conventional cropping systems

In the present investigation, organic and intensive cropping systems were compared on small autonomous drainage plots in limed Luvisoils and Cambisoils as well as non-acid Cambisoils during the period 1995–1998. In the intensive cropping system with balanced nutrient application, the yield of all crops was 38–77% higher than in the organic cropping system. Cropping intensity had no influence on mineral concentration in drainage water, which depended on geochemical soil media. The concentrations of Cl$^-$ and NO$_3^-$ in drainage water were, respectively, 8–22 and 24–80% higher than in the organic system. But at low N application, improvement of fertilisation efficiency increased crop yield and decreased nitrate leaching at the same time. The leached amount of solutes depended mainly upon drainage runoff, which was 6–57% lower in the intensive cropping system than in the organic one, and much less upon its concentration. From this study, organic agriculture has no essential advantage compared with intensive agriculture, considering the amount of leached elements and compounds, and secondarily, crop productivity.Drainage, ruissellement et migration des éléments minéraux dans les systèmes de culture conventionnel et biologique. La comparaison de systèmes de cultures intensif et biologique a été conduite de 1995 à 1998 sur des petites parcelles de drainage autonomes avec des Luvisols et Cambisols chaulés ainsi que des Cambisols non acides. Avec l'agriculture intensive et une application équilibrée de fertilisants, le rendement a été de 38 à 77 % plus élevé qu'avec l'agriculture biologique. L'intensification de l'agriculture n'a pas eu d'effet sur la concentration en éléments minéraux des eaux de drainage qui dépendait surtout de la composition géochimique du sol. Les concentrations en Cl$^-$ et NO$_3^-$ dans l'eau de drainage des parcelles en culture traditionnelle étaient respectivement 8–22 et 24–80 % plus élevées que pour les parcelles en culture biologique. Mais avec l'application de faibles doses d'azote, l'amélioration de l'efficience de la fertilisation a permis d'augmenter le rendement des cultures et de diminuer dans le même temps le lessivage des nitrates. La quantité de solutés lessivés a dépendu surtout du drainage et du ruissellement qui était réduit de 6 à 57 % avec l'agriculture intensive comparativement à l'agriculture biologique et beaucoup moins de la concentration en solutés. D'après cette étude, l'agriculture biologique ne présente pas d'avantage essentiel comparativement à l'agriculture intensive si l'on considère la quantité d'éléments minéraux lessivés et secondairement le rendement des cultures