Summary: In a study conducted during the spring-summer seasons of 2003 and 2004 at the experimental farm of CCORAV in Grotte di Castro, Viterbo, Central Italy, the impact of five rates of a guano-based organic fertilizer on potato yield, tuber quality, nitrogen uptake, and nitrogen use efficiency was evaluated.
A randomized complete block design with four replicates was employed to compare five rates (0, 0.5, 10, 15, 20 t ha-1) of a guano-based fertilizer (10.0N-1.3P-2.5K). The study found that the rate of organic fertilizer did not significantly affect the yield of large size tubers (> 75 mm) and small size tubers (< 45 mm). However, there was a linear increase in the marketable yield of medium size tubers (> 45-75 mm) and total marketable yield with increasing fertilizer rate.
A notable finding was the linear relationship observed between leaf nitrogen concentration at the blooming stage and fertilizer rates, suggesting that the observed effect on marketable yield was likely due to the nitrogen status of the plants. Tuber nitrogen uptake increased with increasing fertilizer rate, indicating a positive correlation between fertilizer application and nitrogen uptake by the plants.
Interestingly, nitrogen use efficiency exhibited an opposite trend, decreasing with increasing fertilizer rate. This suggests that while higher fertilizer rates led to increased nitrogen uptake by the plants, the efficiency of nitrogen use decreased, possibly due to factors such as nutrient leaching or inefficient utilization of nitrogen by the plants.
Overall, the study underscores the importance of optimizing fertilizer rates to maximize potato yield and quality while considering factors such as nitrogen uptake and use efficiency for sustainable agricultural practices.
Publication: Acta Horticulturae
