Levels of bioelements and their relation to the ruminants' needs in the most important pasture-plant species of the wooded dehesa (grazing-land) in the south-west of Spain
1999
Viguera, F.J. | Olea, L. (Universidad de Extremadura, Badajoz (Spain). Escuela de Ingenierías Agrícolas, Dept. de Biología y Producción de los Vegetales)
The Trifolium subterraneum and Orithopus compressus species, together with the gramineae group are considered the most important pasture plants (pratenses) of the wooded 'dehesa' of Extremadura. In the present paper 5 representative "dehesas" (pasture lands) of the south-west of the province of Badajoz (200,000 ha) are studied over a period of two agricultural years (1993-94 and 94-95). Soils and plants were analysed every fortnight approximately, from autumn until the end of spring, for N, P, K, Ca and Mg. Climatologically two different weather conditions were studied, a year of almost average rainfall and another of extreme drought. The nitrogen proportion in both leguminous species was above the required minimum level (even in dry grass), for the ruminant feeding (over 1.5 per cent and up to 3.5 per cent in January and February), whereas there was a deficiency of Nitrogen in the gramineae group from April on. Regarding Phosphorus, as the plant becomes mature a decrease is noted; all the dehesas studied except Manpolín reached lower rates than the minimum required (0.20 per cent). The potassium evolved in a similar way to that of P, although deficiencies (minimum 0.60 per cent) arose only in Campos de Oliva. Its behaviour was similar in both years. Calcium had a similar behaviour in all the dehesas studied along the vegetative cycle. It was always above the minimum level (0.30 per cent) in the leguminous plants, whereas deficiencies arose in the gramineae from April on in both years. Magnesium results were similar to those of calcium.
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