Liming for forages on acid soils of northern Portugal
Abstract
High exchangeable Al and low exchangeable Ca and Mg are the predominant chemical factors limiting forage growth and animal performance in Tras-os-Montes. Two greenhouse experiments and a 2-year field study were conducted to evaluate the effect of calcitic or dolomitic lime applications on yield and mineral composition of forage species that are commonly used, or have the potential of being grown, in Tras-os-Montes. The 1st greenhouse experiment showed that Mg level in the soil, 0.18 cmol$\sb{\rm c}$ kg$\sp{-1}$ of soil, was not a major factor limiting yield since only Lolium multiflorum, of the 11 species studied, had higher yield (P $\leq$ 0.05) when dolomitic lime was applied. Increase in yield due to liming was attributed to an increase in pH from 5.0-5.6 accompanied by a decrease in Al saturation from 79-10% and by an increase in Ca availability to plants. The species ranked as follows according to the magnitude of yield increase due to calcitic lime: Trifolium fragiferum (100%) $>$ Trifolium pratense (84%) $>$ Vicia sativa (77%) $>$ Vicia villosa (56%) $>$ Trifolium repens (45%) $>$ Lolium perenne (39%) $>$ Lolium multiflorum (36%) $>$ Festuca arundinaceae (32%) $>$ Lolium (multiflorum x perenne x perenne) = Trifolium subterraneum (31%) $>$ Dactylis qlomerata (24%). Since hybrid ryegrass is widely used in the region, 8 acidic soils were selected to represent the diversity of granitic soils in Tras-os-Montes. No yield response to lime was obtained in soils having %Al saturation $\leq$59, %Mg saturation $\geq$10, and %Ca saturation $\geq$21. Only in one soil, having 0.05 cmol$\sb{\rm c}$ of Mg kg$\sp{-1}$ of soil, ryegrass yield was increased by dolomitic lime. These results were confirmed by those obtained in the field experiment, in which ryegrass yield was not increased by any of the lime treatments. In the field experiment rye also did not respond to lime which indicates that the cultivar used is well adapted to the acid soils where it was developed. Only in the 2nd growing season hairy vetch yields were increased (P $\leq$ 0.05) by the original addition of calcitic lime which increased pH to 5.9 and decreased Al saturation to 6%. Dolomitic lime increased Mg concentration of all species, except rye, to levels adequate to meet ruminant requirements for Mg. In the field experiment this effect of dolomitic lime was already noticeable in the 1st cutting of the 1st growing season in the locations receiving the higher lime rates. It can be concluded that when liming is required, the use of dolomitic lime should be a good approach, even if no yield response to applied Mg is expected, to improve animal nutrition and to decrease the probability of grass tetany.
Degree
Ph.D.
Advisors
Ahlrichs, Purdue University.
Subject Area
Agronomy
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.