Spatial variability of Regosol chemical atributes in guava management with neem under semi-arid conditions

Abstract

A B S T R A C TConsidering the relevant importance of guava (Psidium guajava) in Northeastern Brazil along with the benefits of neem cake amendments on soil characteristics, this work evaluated the effects of neem cake on chemical attributes of a Regosol under irrigated guava orchard in an alluvial valley of Pernambuco semi-arid region. Evaluations were carried out in two areas (area 1 -with neem cake; area 2 -without neem cake) at three periods: before the first application of neem cake, 90 days after the first application and 90 days after the second application. A regular 8 × 6-point grid was designed in each area and the soil was sampled for total organic carbon, pH, soluble salts (Na + , K + , Ca 2+ and Mg 2+ ) and total nitrogen contents, as well as soil C-CO 2 evolution rate in soil. Geostatistical analysis pointed out the spherical model as the best fit to the studied variables, followed by the Gaussian model, with ranges from 12 to 60.5 m. Neem cake incorporation increased spatial variability and the contents of the evaluated soil chemical attributes.Variabilidade espacial de atributos químicos em Neossolo no manejo da goiabeira com nim no semiárido R E S U M O Considerando a importância do cultivo de goiabeiras (Psidium guajava) para o nordeste do Brasil e os benefícios da aplicação da torta de nim nas características do solo, avaliou-se o efeito da aplicação de torta de nim nos atributos químicos de um Neossolo Regolítico cultivado com goiabeiras irrigadas no semiárido de Pernambuco. Para as avaliações foram usadas duas áreas (área 1 -com nim; área 2 -sem nim) e três períodos, antes da aplicação do nim, 90 dias após a primeira aplicação e 90 dias após a segunda aplicação; assim, 96 amostras de solo foram coletadas em duas malhas regulares de 8 × 6 pontos amostrais e realizadas análises do teor de carbono orgânico total, pH, teores de sais solúveis (Na + , K + , Ca 2+ e Mg 2+ ), nitrogênio total e taxa de evolução C-CO 2 do solo. O modelo esférico foi o que melhor se ajustou às variáveis estudadas seguido pelo gaussiano, com alcances que variaram de 12 a 60,5 m. A incorporação da torta de nim aumentou a variabilidade espacial e a oferta dos atributos de solo estudados.

Using GIS and Geostatistics to Monitoring Spatial Variability in Soil Chemical Properties Impacted by Cultivation Practices

“…Similar findings were reported by Grego et al, (2010), who discovered that pH had the lowest CV (3.5%) and the low variation. In all sampling periods and both locations, pH was the only one with minimal change (Castro et al, 2016). Additionally, high and low pH values of geographic variability have been documented in earlier research (Caniego et al, 2005& Vidal Vázquez et al, 2013.…”

Vis-NIR-SWIR spectroscopy in mapping of soil physical-chemical attributes in areas cultivated with irrigated mango in the Brazilian semi-arid region

“…Other studies have also found a smaller variation in soil pH compared to other soil physical-chemical attributes (Castro et al, 2016;Laekemariam et al, 2018;Sharma et al, 2020). Low pH variability occurs because the pH values are the logarithmic scale of proton concentration in the soil solution, so this variability would be greater if soil acidity were directly expressed in terms of proton concentration (Reza et al, 2017;Moharana et al, 2020).…”

Spatial dependence of attributes of rainfed maize under distinct soil cover conditions

“…Classic statistical analysis was carried out and normality was evaluated by the Kolmogorov-Smirnov test at 0.05 probability level. Thirty soil samples were randomly selected from each field, as suggested by Castro et al (2016), in order to conduct the statistical analysis. The coefficient of variation (CV) was classified according to Warrick & Nielsen (1980) criteria as follows: Low variability (CV < 12%), intermediate variability (12 ≤ CV ≤ 60%), and high variability (CV > 60%).…”