DIAGNOSIS AND SPATIAL VARIABILITY OF SOIL FERTILITY AND CROP PRODUCTION IN A TEAK AREA IN EASTERN PARÁ STATE.

ABSTRACT This study aims to generate the diagnosis and spatial variability maps of soil fertility attributes, as well as teak (Tectona grandis L.f.) production through geostatistics. The study was conducted on a commercial farm in the municipality of Capitão Poço, state of Pará, Brazil. Soil and yield data were collected from 155 sampled georeferenced points and 143 were used in the study (after outlier removal). The collected soil samples were submitted to laboratory analysis to obtain the values of the following variables: pH, organic matter (OM), calcium (Ca), magnesium (Mg) and potassium (K), available phosphorus (P), aluminum (Al), Base Sum (BS), cation exchange capacity at pH 7.0 (T), effective cation exchange capacity (t), base saturation (V%) and aluminum saturation (m %). Thereafter a diagnosis, linear correlation univariate and geostatistical analysis were applied in the resulting data. The univariate statistics showed that normal distribution is not required when evaluating spatial variability of chemical and production variables. Soil fertility diagnosis showed K, OM and P as the most limiting parameters in the commercial teak plot and the importance to fertilize forest areas. Positive correlation was found between P, OM, K with volume per tree. All soil fertility and teak volume variables showed spatial dependence, which enabled the production of spatial variability maps. The variability maps showed to be used complementary with univariate statistics to enable more precise interventions in a teak production area, as it showed the shortage of K in the area and the relation of P and volume per tree.

摘要 本研究旨在通过地统计学（geostatistics）方法，生成土壤肥力属性的诊断结果与空间变异图谱，同时获取柚木（Tectona grandis L.f.）的产量数据。本研究在巴西帕拉州卡皮唐波苏市的一处商业柚木种植园开展。
研究共采集155个带地理坐标的采样点的土壤与产量数据，经异常值剔除后保留143个样本用于后续分析。
采集的土壤样品送至实验室开展分析，获取以下变量指标：pH值、有机质（OM）、钙（Ca）、镁（Mg）、钾（K）、速效磷（P）、铝（Al）、盐基总量（BS）、pH 7.0条件下的阳离子交换量（T）、有效阳离子交换量（t）、盐基饱和度（V%）以及铝饱和度（m%）。
随后对所得数据开展诊断分析、单变量线性相关分析与地统计学分析。
单变量统计结果表明，在评估化学性状与产量变量的空间变异时，无需满足正态分布假设。
土壤肥力诊断结果显示，钾（K）、有机质（OM）与速效磷（P）是该商业柚木种植园最主要的限制因子，同时证实了对林地开展施肥的必要性。
研究发现速效磷（P）、有机质（OM）与钾（K）与单株材积呈显著正相关。
所有土壤肥力指标与柚木材积变量均表现出空间依赖性，据此可生成空间变异图谱。
空间变异图谱可与单变量统计方法互补使用，助力柚木种植区实施精准干预，研究结果同时揭示了研究区域内钾素匮乏的现状，以及速效磷与单株材积的关联关系。