Biological tests in pots with subterranean clover in coastal dry land soils, VI Region of Chile. II. Survey of available phosphorus, sulfur, boron and molybdenum and their relation to nodulation

José Domingo Opazo A.1, Lorena Fernández S. y María Adriana Carrasco R.

The productivity and quality of native dry land pasture of the Coastal Range of the VI Region of Chile, the major feed resource for the livestock of this zone and main source of economic income for its population, could be improved increasing the proportion of better forage species, such as subterranean clover (Trifolium subterraneum L.). However, the adequate establishment of subterranean clover has been impeded probably due to nutrient deficiencies. The objective of this study was to validate a method of pot assays under greenhouse conditions as a quick method for evaluating nutrient deficiencies of P, S, B and Mo. Curanipe (Alfisol) and Marchihue (Inceptisol) series were used. The treatments applied to each pot containing 2 kg of soil and six plants of subterranean clover cv. Trikkala were as follows: the control (T), complete fertilization (FC), FC-S, FC-B and FC-Mo. The plants were cut 79 days after sowing. Aerial dry matter (MSA) yield and the number of nodules were affected by a severe P deficiency, an acid pH (5.1) and exchangeable Al (0.09 cmol (+) kg-1). Aerial dry matter was not affected by B and Mo application. According to the soil fertility degradation, the dry matter increased by two to six times under experimental conditions. Sulfur mineralization and possible SO2 foliage absorption should be considered for S availability interpretation.

Key words: Trifolium subterraneum L., missing element method, dry land soil, Coastal Range.

1 Universidad de Chile, Facultad de Ciencias Agronómicas, Casilla 1004, Santiago, Chile. E-mail: jopazo@uchile.cl.

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