Abstract
The objective of this study was to evaluate the production and persistence of biomass of pearl millet ( Pennisetum glaucum ), guinea grass ( Panicum maximum ) and palisade grass ( Urochloa brizantha ), as well as the release rate of macronutrients and Si and changes in cellulose, lignin and the C/N and C/Si ratios of biomass. The experimental design was a randomized block design, with four replications, in a factorial constituted by three cover crops (pearl millet, guinea grass and palisade grass) and six sampling times (0, 14, 34, 41, 51 and 68 days after desiccation (DAD). The pearl millet produced more biomass and accumulated more N, P, K, Ca, Mg, S, Si and C than the guinea grass and palisade grass. The maximum release rate of macronutrient occurred soon after the desiccation of the cover crops. The decomposition and release rate of nutrients and Si was higher in the biomass of pearl millet, compared to other cover crops. Over time there was an increased C/N ratio, cellulose and lignin content and reduction in the C/Si and decomposition rate of the biomass. The K is the nutrient most quickly available to the soil, and Si has the lowest release rate. Plants with higher biomass production and lower C/Si are more interesting to be used under no-till by offering greater and more persistent ground cover.
Highlights
For the implementation and maintenance of no-tillage system should be used cover crops to keep the soil surface permanently covered with biomass and are able to recycle nutrients and make them available gradually to crops in sucession
The experimental design was a randomized block design, with four replications, in a factorial constituted by three cover crops and six sampling times (0, 14, 34, 41, 51 and 68 days after desiccation (DAD)
The decomposition and release rate of nutrients and Si was higher in the biomass of pearl millet, compared to other cover crops
Summary
For the implementation and maintenance of no-tillage system should be used cover crops to keep the soil surface permanently covered with biomass and are able to recycle nutrients and make them available gradually to crops in sucession. The Panicum maximum and Urochloa brizantha are species with wide adaptability by having strong and deep root system, able to exploit higher volume of soil, so have high drought tolerance and absorption of nutrients in deeper soil layers, can achieve productivity higher than 6 Mg ha-1 (CRUSCIOL; SORATTO, 2007; NUNES et al, 2006), featuring such species as of excellent quality for ground cover in no-tillage system (BARDUCCI et al, 2009) They increase soil biological activity, favor the increase in organic matter content and reduce erosion (VILELA et al, 2011)
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