Abstract ▼ AI-Helper

Organic farming systems based on ecological concepts have the potential to produce sustainable crop yields with no decline in soil and environmental qualities. Recently sustainable agricultural systems, including organic farming, have been rapidly expanding, and development of sustainable farming sy...

Organic farming systems based on ecological concepts have the potential to produce sustainable crop yields with no decline in soil and environmental qualities. Recently sustainable agricultural systems, including organic farming, have been rapidly expanding, and development of sustainable farming systems necessarily must be based on value judgement for key properties of importance for farming. Soil nutrient status in organic farming apple orchard was evaluated in relation to conventional farming to better understand the effects of organic farming system on soil fertility and sustainability. Two adjacent apple orchards, matched by soil type, were chosen for this study to ensure the same pedological conditions except management system. Soil organic matter, total and mineral N, available P, exchangeable cations, and micronutrients were measured at depth of 5-20 cm from May to October in 2006. Various soil physical, chemical, and biological indicators were also measured. Average organic matter contents were 63.3 and 31.0 g/kg in organic and conventional farming, respectively, and the level in organic farming was greater than the recommended level of 25-35 g/kg for fruit trees. Total N content was 3.3 and 1.7 g/kg in average in organic and conventional farming, respectively. Ammonium and nitrate N in organic farming were maintained at relatively stable levels, but in conventional farming the levels were very high in early season due to the chemical fertilizer application. In organic farming apple orchard, available P content in May was lower than that found in conventional farming, but during the growing season available P content was continuously increased and in August the content was more than 1000 mg/kg. The available P contents in the apple orchard soils were greater than the recommended level of 200-300 mg/kg for fruit trees. Organic farming maintained significantly greater exchangeable K, Ca, and Mg levels than conventional farming. Available Cu, Fe, and Mn contents were significantly greater in conventional farming compared with those found in organic farming. However, available Zn extracted in 0.1 M HCl was significantly greater in organic farming soil. Most nutrient levels above crop needs were observed in both conventional and organic farming indicating the potential for negative environmental impacts. Soil physical properties were significantly improved in the organic farming apple orchard in comparison to the conventional farming apple orchard. Bulk density was lower and porosity was higher in organic farming soil. Soil aggregation was also improved in the higher organic matter soil of organic farming. Water holding capacity and infiltration rate were also increased in the soil of organic farming apple orchard. Organic management resulted in significant increases in organic matter, microbial populations and biomass, and enzyme activities of dehydrogenase, alkaline phosphate, protease and urease in the apple orchard soil compared with those found under conventional management. Biological soil quality indicators showed significant positive correlations with soil organic matter content. These results indicated that organic based farming positively affected soil organic matter content, thus improving soil chemical and biological qualities. Although organic inputs cannot easily provide the balance of nutrients needed by the plant, careful and efficient use of manure under organic system is required to avoid any threat to soil and environmental quality.

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