Submitted to: American Forage and Grassland Council Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 10, 2004
Publication Date: June 16, 2004
Citation: Skinner, R.H., Sanderson, M.A., Tracy, B.F. 2004. On-farm comparisons of carbon uptake and partitioning to roots in simple and complex pasture mixtures. American Forage and Grassland Council Conference Proceedings. 13. [CD-ROM]. Technical Abstract: Forage yield on pastures is a function of net photosynthetic inputs (photosynthesis minus respiration) and the partitioning of those inputs between above- and below-ground tissues. While many studies have looked at aboveground productivity of pastures, much less information is available on canopy photosynthetic rates or on root production and distribution in the soil profile. As part of an on-farm study to compare dry matter yield of 2-, 3-, and 11-species forage mixtures, we measured net canopy photosynthesis on 7 to 8 dates from early-April to early-October in 2000-2002. We also measured root distribution to a depth of two feet in mid-September each year. Net photosynthetic rate did not differ significantly among mixtures although there was a trend towards greater net photosynthesis as the number of species increased, especially during the summer (June through August). The 11-species mixture also had greater root biomass than the other two mixtures, and roots were distributed deeper in the soil profile as the number of species in the mixture increased. Deeper rooting depth could improve productivity during summer drought by increasing access to available soil moisture.