Nitrogen and Potassium Fertilization in a Guava Orchard Evaluated for Five Cycles: Effects on the Plant and on Production

ABSTRACT Guava response to fertilization can be monitored through plant tissue analysis. Correct interpretation of these results, based on standard levels, is of great importance for correct nutrient management of the crop. However, standard levels are constantly criticized for not considering interactions among elements. To improve the nutritional diagnosis of ‘Paluma’ guava (Psidium guajava L., Myrtaceae), an experiment was conducted using nitrogen fertilization (0, 0.5, 1.0, and 2.0 kg per plant per cycle of N, with urea as a source with 45 % N), and potassium fertilization (0, 0.55, 1.1, and 2.2 kg per plant per cycle of K2O, with potassium chloride as a source with 60 % K2O) in an irrigated commercial area for five consecutive cycles, 2009 through 2012, observing the influence of fertilizers and climate and assessing yield and leaf element content, using the concept of isometric log ratios (ilr) to interpret leaf analysis results (N, P, Ca, Mg, K, and S). This paper showed that nutrient balances and nutrient concentration values can be interpreted coherently using compositional data analysis. Ranges of nutrient balances also were established for “Paluma” guava and validated through ranges grounded in nutrient contents currently used in Brazil. Nitrogen fertilization increased “Paluma” guava yield. The 0.5 kg N application rate per plant and the other studied treatments practically showed the same results, and their values were affected by pruning time as well as the nutrient balances

Nitrogen and Potassium Fertilization in a Guava Orchard Evaluated for Five Cycles: Effects on the Plant and on Production

ABSTRACT: Guava response to fertilization can be monitored through plant tissue analysis. Correct interpretation of these results, based on standard levels, is of great importance for correct nutrient management of the crop. However, standard levels are constantly criticized for not considering interactions among elements. To improve the nutritional diagnosis of 'Paluma' guava (Psidium guajava L., Myrtaceae), an experiment was conducted using nitrogen fertilization (0, 0.5, 1.0, and 2.0 kg per plant per cycle of N, with urea as a source with 45 % N), and potassium fertilization (0, 0.55, 1.1, and 2.2 kg per plant per cycle of K 2 O, with potassium chloride as a source with 60 % K 2 O) in an irrigated commercial area for five consecutive cycles, 2009 through 2012, observing the influence of fertilizers and climate and assessing yield and leaf element content, using the concept of isometric log ratios (ilr) to interpret leaf analysis results (N, P, Ca, Mg, K, and S). This paper showed that nutrient balances and nutrient concentration values can be interpreted coherently using compositional data analysis. Ranges of nutrient balances also were established for "Paluma" guava and validated through ranges grounded in nutrient contents currently used in Brazil. Nitrogen fertilization increased "Paluma" guava yield. The 0.5 kg N application rate per plant and the other studied treatments practically showed the same results, and their values were affected by pruning time as well as the nutrient balances

Nitrogen and Potassium Fertilization in a Guava Orchard Evaluated for Five Cycles: Soil Cationic Balance

ABSTRACT Soil fertility evaluation through soil analysis traditionally does not consider interaction among elements. To include the interaction effect in interpretation of soil analyses, an experiment was conducted to evaluate the effect of nitrogen fertilization (0, 0.5, 1.0, and 2.0 kg N per plant per cycle) with urea (45 % N) and potassium fertilization (0, 0.55, 1.1, and 2.2 kg K2O per plant per cycle) with potassium chloride (60 % K2O) on soil cationic balance. The experiment was carried out in an irrigated commercial production area of ‘Paluma’ guava, for five consecutive cycles, 2009 through 2012, using the concept of isometric log ratio (ilr) to evaluate soil cationic balance through [K, Ca, Mg | H+Al], [K | Ca, Mg] and [Ca | Mg] balances. The compositional data analysis showed to be a suitable tool to interpret the soil cationic balance given that the soil cationic balances value was changed by nitrogen fertilization and potassium as well as the soil pH value and the concentration of K in the soil. The soil cationic balances also changed by the variations of in climate conditions at period of soil sample. An application rate of 0.55 kg K2O per plant per cycle was considered sufficient to keep K soil concentration above 1.6 mmolc dm-3