Nutrition of intensive pastures in the summer rainfall areas of southern Africa

Abstract

Consideration is given to the current state of knowledge regarding the nutrition of cultivated pastures in the summer rainfall areas of southern Africa. Research efforts over the years have concentrated on the nitrogen (N) requirements of pastures, with relatively little significant work being undertaken on phosphorus (P), potassium (K) and lime. The numerous N response curves derived in cutting trials provide a useful basis for predicting N requirements under cutting‐and‐removal type utilization, but are of little value in predicting N requirements under grazing. The critical roles of P, K and lime in pasture productivity and persistence have been demonstrated in field trials undertaken in the Natal Midlands and south‐eastern Transvaal. Soil test calibrations, established for several important pasture species on Natal soils, have been found to provide a sound basis for predicting P, K and lime requirements of pastures. In considering the direction of future research, it is suggested that considerable potential exists for more efficient fertilizer and lime usage; research efforts should therefore be channelled in that direction.

Die tans beskikbare kennis van die voeding van intensiewe weidings in die somer reënvalgebiede van suidelike Afrika word oorweeg. Navorsingspogings deur die jare is hoofsaaklik toegespits op die stikstofbehoeftes (N) van weidings, terwyl relatief min betekenisvolle werk gedoen is op fosfor (P), kalium (K) en kalk. Die baie N‐reaksiekrommes wat uit snyproewe verkry is vorm ‘n nuttige basis vir die voorspelling van N‐behoeftes onder sny‐en‐verwyder benutting, maar is van min waarde in die voorspelling van N‐behoeftes onder beweiding. Die kritieke rol van P, K en kalk in weidingsproduktiwiteit en meerjarigheid is in veldproewe wat in die Middellande van Natal en Suid‐Oos Transvaal uitgevoer is, gedemonstreer. Daar is aangetoon dat grondontledingskalibrasies, wat vir verskeie belangrike weidingspe‐sies op Natalse gronde ontwikkel is, ‘n grondige basis vorm vir die voorspelling van P, K en kalkbehoeftes van weidings. Met die oorweging van die rigting van toekomstige navorsing, word aangetoon dat aansienlike potensiaal vir meer doeltreffende bemesting en kalk verbruik bestaan; navorsingspogings behoort dus in daardie rigting gekanaliseer te word.

Additional index words:

• Fertilizers
• grass
• legume
• lime
• minerals