Effect of Eucalyptus-Wood-Based Compost Application Rates on Avocado (Persea americana Mill) Foliar Nutrient Content and Fruit Yield

Abstract

Background: The effects of different fertilizer types and their application rates on leaf nutrient content and avocado yield are unclear. An evaluation of eucalyptus-wood-based compost applied at 0, 5, 10, and 15 t ha−1 year−1 on foliar nutrient content, yield, and fruit size distribution (%) was completed at Mooketsi and Politsi, Limpopo Province, South Africa, from 2016 to 2018. Methods: A completely randomized block design with three replicates was used. Data were collected annually, and fruit size was classified as classes; 1 (>275 g), 2 (197–274 g), 3 (148–196 g), and 4 (0–147 g). Results: Leaf N, P, K, Ca, Mg, Fe, Mn, Na, Cu, and Zn, fruit yield and size distribution (%) were significantly (p < 0.05) affected by compost quantity and proportionally increased with application rates in each year. Compost had cumulative effects on the measured parameters; the highest values were recorded in 2018 under a 15 t ha−1 application rate, which corresponded to the highest yield (19.6 t ha−1) and the largest proportion of fruits in class 1. Conclusions: The ≥10 t ha−1 year−1 application rate can be used, though the compost saturation levels of the soils should be determined to avoid possible danger of nutrient toxicity if high application rates are continuously used for >3 years.