Growth response to fertilizers on Natal sweet orange trees

The effects of three levels of organic and inorganic fertilizers on stalk growth of orange trees were evaluated in Red-Yellow Podzolic soil. It was considered the effects of cattle manure, chicken manure, castor bean bran, as well as Chilean nitrate, ordinary superphosphate and muriate of potash on culm diameter. Measurements made 10 cm above the graft point indicated positive effect of nitrogen and phosphorus on increasing stalk diameter. Potash did not contribute to development but yielded negative effect confirming precedent results. The organic fertilizers did not differ among themselves and had less effect than the mineral sources. The organic fertilizers gave better response when intermediate dosages were applied.