Root biomass of five tropical grass pastures under continuous grazing in Brazilian Savannas
1999
Kanno, T. (Japan International Research Center for Agricultural Sciences, Tsukuba, Ibaraki) | Macedo, M.C. | Euclides, V.P.B. | Bono, J.A. | Santos, J.D.G.Jr. | Rocha, M.C. | Beretta, L.G.R.
The purpose of this hay is to compare the root biomass among five tropical grasses, which affects the level of organic matter supply into soil and mineral nutrients acquisition. Experimental pastures of Brachiaria decumbens cv. Basilisk (BD). B. brizantha cv. Marandu (BB). Panicum maximum cv. Tanzania (TA), P. maximum cv. Tobiata (TO) and Andropogon gayanus cv. Baeti (AN) were established with two different levels of phosphorus and potassium. These pastures were grazed for three years, and then root biomass was measured in 0-10, 10-20 and 20-40cm of soil layers. Measured root biomass represented 53-76% of total biomass of the five grasses. Among the five grasses, root biomass level per square meter was in the order of BB BD TA TO AN, with the root biomass of BB significantly higher than those of the other grasses. Root biomass in the high fertilized soil was greater than those with low fertilizer levels. Root biomass decreased quickly with the increase of soil depth, whereas the percentage of root biomass to dry soil of BB was highest among the five grasses in all of the soil layers. It is concluded that BB is the best option to be introduced in crop-pasture rotation for soil quality improvement, in terms of quantity and distribution of root biomass. The relationship between root biomass and growth response of the examined species to soil fertility is also discussed
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