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.

Seasonal nutrient content variation in avocado leaves of ‘Geada’, ‘Fortuna’ and ‘Quintal’ genotypes

“…There are no consistent references to categorize N levels for plants of these genotypes under the Brazilian edaphoclimatic conditions. The limits described in Brazilian references such as Leonel et al (2012) and Rosane (2022) are mostly based on works developed from the 1960s to the 2000s in Australia, South Africa and North America, which are practically the same as those observed in reviews by Newett et al, (2018) and Mohale et al (2022). In these references, N contents between 22 and 26 g kg -1 are considered adequate, while the most recent recommendations for the state of São Paulo report levels from 16 to 20 mg kg -1 (TEIXEIRA et al, 2022).…”

“…After the month of October, P levels decreased to values between 1.0 and 1.5 g kg -1 in the other evaluations and varied little within each genotype (Figure 3B). Such P values would be considered sufficient, since they are in the range from 0.8 g kg -1 to 2.5 g kg -1 (LEONEL et al, 2012;NEWETT et al, 2018;MOHALE et al, 2022;ROSANE, 2022, TEIXEIRA et al, 2022. Although the P levels in the leaves of the three genotypes remained within a very narrow range (between 1.0 and 1.5 g kg -1 ), P levels in 'Quintal' genotype tended to be around 20% higher than those of 'Geada' genotype, with those of 'Fortuna' genotype remained at intermediate values between those of 'Quintal' and 'Geada' genotypes.…”

“…Literature references indicate that the sufficiency range for K content in leaves can be quite wide, with values between 7.5 and 20 g kg -1 (LEONEL et al, 2012;MOHALE et al, 2022;ROSANE, 2022, TEIXEIRA et al, 2022.…”

Effect of eucalyptus wood-based compost application rates on soil chemical properties in semi-organic avocado plantations, Limpopo province, South Africa

“…The compost is usually seen as a decent source of nitrogen (N), phosphorous (P), potassium (K), micronutrients, and humic substances essential for plant growth [ 6 ]. Soil nutrients like N, P, K, Ca, Mg, Zn, Cu, B, and Fe are important for the production of fruit trees like avocado [ 15 ]. These nutrients should be readily available to the trees because they are required in the various physiological functioning of the plant ranging from germination up to fruit ripening [ 7 ].…”

“…Commercial agriculture has been and still relies on the use of inorganic fertilizers for increasing crop yield [ 13 ]. However, the inorganic fertilizers do contribute substantially to environmental degradation and promote high loss of nutrients through leaching [ 14 , 15 ]. The high losses of nutrients are caused by the poor health of the soil system leading to a reduction in the cation exchange capacity of the soil [ 5 ].…”