Use Efficiency and Leaching of Nutrients in Organic and Conventional Cropping Systems in Sweden

Abstract

In the past few years, organic farming has been proposed as a possible way of reducing N leaching from agricultural soils and improving the use efficiency of plant nutrients. This is, to a large extent, considered to be attributed to the fact that synthetic fertilisers are not allowed in such systems and the N inputs mainly originate in various types of organic manures. In this overview, results from a number of Swedish field studies are presented in which crop yields, nutrient-use efficiencies and leaching in organic and conventional systems are evaluated. Some studies were conducted in lysimeters and others in large tile-drained field plots. In two lysimeter experiments, leaching of N derived from either poultry manure or red clover (Trifolium pratense L.) green manure were compared with fertiliser N, all labeled with 15-N. In the lysimeters on which poultry manure was applied, 32% of N applied leached during three years, whereas only about 3% leached in ammonium nitrate fertilised lysimeters. In plots on a sandy soil, annual N leaching loads averaged over the whole 6-yr crop rotation reached 39 kg N ha -1 in the organic rotations and 25 kg N ha -1 in the conventional rotation. Phosphorusleaching loads were overall small in all systems, whereas K leaching was highest in the conventional rotation (i.e., on average, 27 kg ha -1 yr -1 ). In terms of crop yields, they were reduced by 20 to 80% in the organic rotations compared to the same crops in the conventional rotations. This was explained in terms of N deficiency, weed competition, and infestation of crop diseases in the organic systems. These results suggest that organic crop production uses agricultural soils less efficiently, with no benefit for water quality.

The effect of fertilizer and N application rate on nitrogen and potassium leaching in cut grassland

“…Our research shows that water percolation together with nutrient leaching is reduced with increasing yield . Similarly to findings by Bergström et al (2008) this result demonstrates that N leaching is not lower when using organic fertilizers compared to mineral fertilizers. Several previous studies (Hansen et al, 2000;Knudsen et al, 2006) have found that N leaching was lower in organic systems and the reason for it was lower N input.…”

“…Advanced use of fertilizers has resulted in significantly increased agricultural productivity, but simultaneously in a higher environmental pressure (Mondelaers et al, 2009), of which contamination of surface and groundwater by plant nutrients is among the most serious Bergström et al, 2008;Gali et al, 2012). Nutrient leaching is considered the most problematic in regions where precipitation exceeds evaporation considerably.…”

“…Bergström et al (2008) suggest that in organic systems, which depend on renewable and natural fertilizer sources N mineralization and crop N demand are poorly synchronized making it more vulnerable to leaching than inorganic fertilizers, especially under the cold and humid climate conditions. Ten Berge et al (2002) and Schröder et al (2010) state that it does not matter much from a leaching point-of-view whether the N requirement is met with mineral fertilizer-N or with plant-available N from manure; it is the quantity of N in the system rather than the source of N, which determines the environmental impact (Watson, Younie, 1995).…”

Agroforestry—The Next Step in Sustainable and Resilient Agriculture

“…In Swedish studies, Bergström et al concluded that organic sources of nitrogen leached more than conventional fertilizers. They attributed this to the fact that the manures and legume cover crops released the most nutrients during fallow periods or at times that did not sync with nitrogen demand of the crop [50].…”

Organic Farming and Soil Carbon Sequestration: What Do We Really Know About the Benefits?

“…Together, there is evidence that the overall C balance of soil, provided similar amounts of manure are available, is not systematically different between, on the one hand, mixed (organic) systems where manure is applied within single farms or, on the other hand, specialized conventional farming that selectively spreads high rates of manure but only on a fraction of the conventional land. But it should be noted that excessive organic fertilization, be it in conventional or organic systems, may cause substantial environmental problems, for example nutrient leaching (Bergström et al 2008), which needs to be tackled by sustainable management practices.…”