Nitrogen and phosphorus absorption rythm and NP fertilization response in garlic

Rafael Ruiz S.1

A factorial experirnent, with five levels of nitrogen (0, 75, 150, 225, and 300 kg of N/ha) and four leveis of phosphorus (0, 45, 90, and 135 kg of P2O5/ha), indicated a strong response of garlic to N, both in yield and in qua(ity. Yield increased up fo a dose of 150 kg of N/ha, and quality, up to 225 kg of N/ha. Response of garlic to P was low, even when the P-Olsen analysis of the soil was low (3 ppm). It was postulated that garlic has a high P extracting efficiency. Nitrogen extraction was closely related to the amount applied, up to the level for maximum yield, when extraction was 140 kg of N/ha. Higher doses did not increase N extraction and absorption efficiency was 46%, at maximum yield. Nitrogen absorption was always higher than DM. accumulation in the plant, specially during the first stages of growth. Phosphorus extraction, with maximum production, wasabout 22 kg/ha. As absorption from the soil was about 17 kg of P/ha, when N was not limiting, only 5 kg of P came from the fertilizer applied, with and efficiency of 12%, for garlic in this type of soil. Finally, no differences were observed due fo time of applying the N fertilizer, or dividing the dose in several applications, during the growing season.

1 Estación Experimental La Platina (INIA), Casilla 5427, Santiago, Chile.