Soil attributes under different crop management systems in an Amazon Oxisols

Abstract

Soil biological properties have a high potential for use in assessing the impacts of crop systems. The objective of this study is to evaluate the effects of cropping systems on the biological attributes of an oxisol in the Amazonian state of Pará. The treatments consisted of approximately 20-year-old secondary vegetation, recovered pasture, no-tillage systems (NT) maintained for 4 and 8 years after planting with corn (Zea mays L.) and soybean (Glycine max L.), and conventional tillage (CT) systems every 2 years after planting with rice (Oryza sativa L.) and soybean. The microbial biomass to nitrogen ratio was higher in the NT system (0.68 mg kg -1 ), and the NT system had greater microbial NT8. Thus, the contributions of organic matter from straw improved the soil quality in these areas. The total organic carbon (TOC) content was greater in the secondary forest and CT areas (46.7 and 48.0 mg kg -1 , respectively), potentially due to the higher amounts of organic matter and organic matter mineralization in these areas. However, the largest TOC stocks were observed in the pasture, which corresponded with greater carbon storage (63.5 Mg ha -1). By contrast, the no-till systems were not efficient for storing C, with concentrations of 5.0 and 5.3 Mg ha -1 in NT-4 and NT-8, respectively. These results may reflect the short period that these systems were adopted and the vast microbial activity that was observed in these areas, with microbial quotients of 8.03 and 10.41% in NT-4 and NT-8, respectively.

Organic Fertilization with Residues of Cupuassu (Theobroma grandiflorum) and Inga (Inga edulis) for Improving Soil Fertility in Central Amazonia

“…In general, the average levels of K in the soil observed in this study were low (<0.05-0.10 cmol c kg −1 ), according to Moreira and Fageria [13] criteria. Soils in Amazonia hold low K contents [6,13,19,20] and, due to the relatively high demand many native plants have for it, K becomes one of the most limiting nutrients for Organic Fertilizers producing fruits in this region [21]. Studies conducted in the Manaus region have shown K to be the most exported nutrient through agroforestry products originating from Amazonian native species, such as cupuassu, peach palm (Bactris gasipaes), and assai (Euterpe oleracea), with higher concentration in shells, seeds, and infructescence petioles, which must be reincorporated into the planting areas to maintain sustainability [22].…”

“…The often wasted cupuassu tree fruit shells could be used in contributing to fertilize the soils. The recycling of these wastes, as well as a better use of natural resources, has become very important when it comes to sustainable agriculture since it reduces production costs and minimizes environmental impact [5,6]. Furthermore, organic residues can bear phytopathogenic suppressing microorganisms present in the soil, in addition to stimulating the growth of a more diversified and competitive/suppressing microbiota, reducing the occurrence of plant diseases [7,8].…”

Inorganic Nitrogen Fractions in Soil Under Different Uses and Management Systems in the Brazilian Eastern Amazon

“…Previous studies carried out in Amazon soils on N fractions in different agricultural systems investigated, in particular, total N (Silva Júnior et al, 2018) andmicrobial N (Aragã o et al, 2012;Lopes et al, 2015) for evaluation of the biological response given by the microbiota. The inorganic N fractions determination can help to better understand the potential N availability.…”

Weed control methods and coffee shrub residue effects on carbon stocks in a Latosol under conservation management practices

“…Soil management and practices must assure maintenance or enhancement of soil biological, chemical, and physical features, consequently providing sustainable production and crop yield (Lopes et al, 2015). Certain fractions of SOM play key role on maintaining soil quality, being more sensitive to management practice effects (Ebeling et al, 2011).…”