Variabilidade espacial de características químicas em um solo salino-sódico.

Abstract

The objective of this work, had to study the spatial variability of chemical characteristic in the saline-sodic soil. The experiment was carried out in the Irrigated Perimeter of Sao Goncalo, Sousa, Paraiba, in Experimental Station area of the Embrapa Algodao. The experimental unit was of 2912m2, where were demarcated 182 observations points, ordered in a square mesh of 4,0x4,0m. The soil samples were colletecd at the profundity of 0-3 Ocm, in each experimental mesh point. The chemical determinations were realized in the Salinity and Irrigation Laboratory, belonging Agricultural Engineering Departament of Federal University of Paraiba, Campina Grande-PB. The data analysis were realized through descriptive statistic and geoestatistic. The descriptive analysis were realized with objective of to observe the data deportment usually of and the geoestatistics analyses through of the semivariogram view of, to examine the spacial structure of evaluated chemical variable. From of parameter estimate fitted to semivariogram of model was, realized the krige, in the mesh of 2,0x2,0m, totalized 624 points, to construction of isolines maps. By descriptive analysis showed that the data of pH presented variation fewer (CV=11,06%), followed of CTC (CV=39,43%), PST (CV=43,06%), K (CV=48,24%), Na (CV=65,93%), CE (CV=79,20%), Ca (CV=80,43%) and Mg (95,68%). The analysis of frequency distribution, showed that the data of CTC, followed a normal distribution. The data of CE, K and Mg followed a log-normal distribution. The another chemical variable not fbllwed non type of distribuition evaluated. The geoestatistic analysis realized showed that the models best of to semivariogram fited of data of chemical variable, PST, CE, CTC, K, Ca and Na was the spherical. The data of pH and Mg not suggested structure of spacial dependence, when analised, the assesment total of data, but, after the expuged of data considerate discrepancy, in case of Mg and data that stayed characterized a trend in case of pH, was feasible to fit gaussiano and linear models, respectively, to pH and Mg. The semivariogram analysis showed spatial structure with medium scope of 21,15,12, 12, 25, 27, 23 and 16m, respectively, to pH, CE, PST, K, Ca, Mg e Na. The chemical variable PST, K and the Ca, suggested fort spatial dependence, while, the another suggested moderate spatial dependence. The isolines maps, obtained the leave of estimated values by krige of process, permited a visual of regions of variability minor and major for each chemical variable analyzed, the what is important at the recommendation from mangeable this regions, as also in the experimental delineatement of futuros works in the area.