Nitrogen Doses and Humic Substances in Custard Apple Nutrition

Abstract

Custard apple production (Annona squamosa L.) in the Brazilian Northeast occurs throughout the year. Its management involves pruning, irrigation, and proper nutrition. The objective of the present work was to verify the influence of different doses of nitrogen and the use of humic substances on soil chemical attributes and tree custard apple nutrition. The experiment was conducted in a commercial orchard in the municipality of Anagé, Southwest region of the state of Bahia, in a randomized block design in a 4 x 2 factorial scheme, four nitrogen doses (0, 284, 568 and 852 g per plant, urea) with and without the application of humic substances (Ks100), with 4 replicates. Soil chemical characteristics, macro and micronutrient contents were evaluated in the leaves of the custard apple tree. Nitrogen rates reduced soil pH and the availability of calcium, magnesium and boron. The application of humic substances increased the content of potassium in leaves. Under the conditions studied, high nitrogen doses influence soil fertility and the application of humic substances does not improve the absorption of most of the nutrients, except potassium, and it did not influence the chemical attributes of the soil.

Nutrient content and accumulation in mini lettuce as a function of fertigation management strategies

“…Contents of B and Fe were influenced by N in IC, in which the application of 100 kg/ha N in fertigation increased significantly in 8.21 and 11.87% the contents of these micronutrients when compared with the highest dose (Table 2). This increase in B content can be related to the lower decrease in soil pH due to the lower dose of urea applied as a nitrogen fertilizer source, resulting in a better B availability in soil and consequently increasing the possibility of root extraction (Awaad et al, 2016;Bahia et al, 2019). In this context, the increase observed in Fe content may be related to a greater B uptake by the lettuce, since, according to literature, B influences in availability, uptake and translocation of nutrients such as P, K, Zn, Fe and Cu in plants (Shireen et al, 2018).…”