Characterization of soils cultivated with cassava under different managements

ABSTRACT Although cassava is an undemanding crop in terms of soil chemical fertility, the scarcity of nutrients affects crop productivity, and it is common to cultivate it in soils with low natural fertility, as occurs in Coastal Tablelands. In this context, the present study aimed to evaluate the physical and chemical attributes of soils cultivated with cassava under different managements. The study was carried out in the municipality of São Felipe, located in the landscape unit of Coastal Tablelands, Bahia state, Brazil. Fifteen properties were selected to evaluate the characteristics of soils cultivated with cassava under different types of management. Soil sampling was carried out during the months of October and November 2018, a dry period in the region. The medium-textured soil was predominant in the different areas of management of cassava cultivation. Most areas showed pH below the recommended range for cassava (5.5 to 6.5), base saturation below 50% and low phosphorus, potassium, calcium, and magnesium contents, according to the crop’s nutritional needs. The first two principal components explained 84.65% of the total variance. Thus, it was possible to verify that the diversity of management of cassava production areas results in high or very high variability of soil chemical attributes. The attributes pH, P, Al, H + Al, V, CEC and OM are the most representative in the distinction of soils of the cassava cultivation areas evaluated.

摘要：尽管木薯对土壤化学肥力要求较低，但养分匮乏仍会对其作物生产力造成负面影响；而在巴西沿海台地（Coastal Tablelands）这类区域，人们通常会在自然肥力偏低的土壤中种植木薯。基于此背景，本研究旨在评估不同种植管理模式下木薯种植土壤的理化属性。本研究在位于巴西巴伊亚州（Bahia state）沿海台地景观单元内的圣费利佩（São Felipe）市镇开展，共选取15处地块以探究不同管理模式下木薯种植土壤的特性。土壤采样工作于2018年10月至11月进行，该时段为当地旱季。研究区域内的木薯种植管理地块均以中质地土壤为主。多数区域的土壤pH值低于木薯种植推荐范围（5.5~6.5），盐基饱和度低于50%，且按照木薯的营养需求标准，其磷（Phosphorus, P）、钾（Potassium, K）、钙（Calcium, Ca）、镁（Magnesium, Mg）含量均处于较低水平。本研究的前两个主成分解释了总方差的84.65%，由此可证实，木薯种植区域的管理模式多样性会导致土壤化学属性呈现高度乃至极高的变异性。其中，pH值、磷（P）、铝（Aluminum, Al）、氢铝总量（H + Al）、盐基饱和度（V）、阳离子交换量（Cation Exchange Capacity, CEC）以及有机质（Organic Matter, OM）等属性，是区分本研究中各木薯种植土壤的最具代表性指标。