Abstract
Tillage systems strongly impact nutrient transformations and plant availability. Therefore, the objective of this study was to assess the impacts of conversion of conventional tillage (CT) to no-till (NT) with a mixture of cover crops and green manure as nutrient uptake in a fertilized melon (Cucumis melon) in a semi-arid region of Brazil. Two fields experimental involved randomized blocks design, in a split-plot scheme, with four replication treatments included three types of cover crops and two tillage systems (conventional and no-till). Subsamples of plant cocktails were used to assess the biomass production. Soil samples were analyzed during the melon growth for determination of soil moisture by the frequency domain reflectometry (FDR) probe. Soil solution samples were extracted with ceramic cups from each treatment, and analyzed for determination of TP, Na+, Ca2+, Mg2+, S and NO3-N. Mobility of these elements was assessed in relation to management and different cover crops. The data showed slight or no strong effect of plant cocktails composition on nutrients dynamics in soil under melon. However, without incorporation of biomass and slower decomposition of residue mulch retained on the surface, risks of leaching losses were lower under NT than CT system. A higher concentration of cations in CT (for example, Ca+2 ~ 42.07 mg L-1) may be attributed to high soil moisture content and faster rate of mineralization of the biomass incorporated. Concentration of P was higher in top soil layers depth in NT system (~ 6.65 mg L-1 at 15 cm) because of the deposition of plant cocktail biomass in soil surface with low SOM contents placement of fertilizer, and possible formation of calcium phosphate with low solubility. Relatively, high concentration of NO3-N (~ 60.16 mg L-1) in CT was attributed to increase in decomposition of soil organic matter (SOM) and crop residues incorporated into the soil. Key words: Macronutrient, soil fertility, cover crop, soil management, Cocumis melo, Caatinga.
Highlights
Soils of the semi-arid regions have been prone to degradation because of change in land cover associated with different land uses, mismanagement, and harsh climate (Lal, 2004)
Concentration of P was higher in top soil layers depth in NT system (~ 6.65 mg L-1 at 15 cm) because of the deposition of plant cocktail biomass in soil surface with low soil organic matter (SOM) contents placement of fertilizer, and possible formation of calcium phosphate with low solubility
High concentration of NO3-N (~ 60.16 mg L-1) in conventional tillage (CT) was attributed to increase in decomposition of soil organic matter (SOM) and crop residues incorporated into the soil
Summary
Soils of the semi-arid regions have been prone to degradation because of change in land cover associated with different land uses, mismanagement, and harsh climate (Lal, 2004). In the semi-arid regions of Brazil, Pereira Filho et al 235 conversion of the natural thorn forest (caatinga) into arable land is causing loss of soil organic matter (SOM), depletion of nutrients, and accelerated erosion (Wick et al, 2000). Sustainability of land use systems depends on adoption of conservation agriculture (CA) methods which use cover crops to generate enough dry biomass to provide a continuous soil cover throughout the year. Residues of plants cover conserves soil water by reducing runoff and evaporation, increasing water storage in the effective rooting depth, increasing plant-available water capacity, and increasing net primary production by reducing risks of drought and decreasing losses of plant nutrients by runoff, leaching and erosion (Lal, 2013)
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