Abstract
The conservation tillage systems is based on the surface protection by crop residue and reduced soil disturbance. These two principles can favor the soil quality and promote sustainable agricultural systems. The study was developed with the objective of measure soil microbial biomass, soil basal respiration, enzymatic activity and soybean yield in conservation systems cultivated with cover crops species in the Northeastern Cerrado. The experiment was carried out in 2016/2017 and 2017/2018 cropping seasons, performed in a randomized blocks design. The treatments were soil tillage systems allocated in the main plots: no-tillage (NT) and minimum tillage (MT) and the cover crops were allocated in the subplots: Pennisetum glaucum (millet), Urochloa ruziziensis (brachiaria), Crotalaria spectabilis (C. spectabilis), Crotalaria ochroleuca (C. ochroleuca), Pennisetum glaucum + Crotalaria spectabilis (millet + C. spectabilis) and spontaneous plants with three replicates. The evaluated variables were dry mass (DM) production and nutrient accumulation in cover crops; soil biological properties, namely microbial biomass carbon and nitrogen (MBC and MBN, respectively), respiration, metabolic quotient (qCO2), dehydrogenase enzymatic activity (DH), fluorescein diacetate (FDA); and soybean yield. The higher production of dry mass and nutrient cycling occurs with the intercropping millet + C. spectabilis and single millet. The highest soybean yield occurs in succession to C. ochroleuca and intercropping of the millet + C. spectabilis. Cover crops in conservation systems improve soil microbial quality and increase soybean yield.
Highlights
The agricultural expansion in the Northeastern Cerrado is a result of good soil management practices, especially lime application, improved fertility through mineral fertilization and proper phytosanitary management, which make this region, partly situated in MATOPIBA, one of the last Brazil’s agricultural borders (Almeida et al 2018)
The treatments were soil tillage systems allocated in the main plots: no-tillage (NT) and minimum tillage (MT) and the cover crops were allocated in the subplots: Pennisetum glaucum, Urochloa ruziziensis, Crotalaria spectabilis (C. spectabilis), Crotalaria ochroleuca (C. ochroleuca), Pennisetum glaucum + Crotalaria spectabilis and spontaneous plants with three replicates
The higher accumulation of N, Ca, Mg and Cu in plants grown in MT in relation to NT is due to the disking tillage in the 0–0.3 m layer, which promotes root growth of cover crops during the first year of the experiment
Summary
The agricultural expansion in the Northeastern Cerrado is a result of good soil management practices, especially lime application, improved fertility through mineral fertilization and proper phytosanitary management, which make this region, partly situated in MATOPIBA, one of the last Brazil’s agricultural borders (Almeida et al 2018). Merrill), which presents good adaptation and high yield, is the crop with the largest planted area in the Northeastern Cerrado. Due to the good profitability of soybean, the cultivation system is little diversified, resulting in large monoculture areas. In this production system, cover crops are rarely included, resulting in low production of crop residues and insufficient soil cover throughout the year (Merten et al 2015). Low soil cover may make no-tillage system unfeasible and low residue production compromises soil organic carbon stocks, nutrient cycling, microbiological activity and, soil quality (Pacheco et al 2017; Derpsch et al 2014)
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