title: Phosphorus and Defoliation Interact and Improve the Growth and Composition of the Plant Community and Soil Properties in an Alpine Pasture of Qinghai-Tibet Plateau.
abstract: Pasture degradation caused by overgrazing and inappropriate fertiliser management is a major production and environmental threat in Qinghai-Tibet Plateau. Previous research has focused on the effects of mixed nitrogen (N) and phosphorus (P) fertiliser and reduced grazing pressure on the plant community of the grassland; however, the role of P and how it interacts with various defoliation (the process of the complete or partial removal of the above-ground parts of plants by grazing or cutting) intensities on the plant and soil of the grassland ecosystem have not been quantified. A field experiment was conducted to quantify how P application in combination of defoliation pressure could impact the dynamic change of the plant and soil in a native alpine grassland ecosystem of the Qinghai-Tibet Plateau, China, from May 2012 to September 2014. A split-plot design with 4 replicates and repeated measures was used to determine the growth and composition of plant community and soil physical and chemical properties under various levels of P fertiliser and defoliation intensity. The results showed that applying 20 kg P/ha increased the herbage yield of Melissitus ruthenica by 68% and total pasture yield by 25%. Close defoliation favoured the growth and plant frequency of the shorter species, whereas lax defoliation favoured that of the taller plant species. Medium P rate and cutting to 3 cm above ground gave an overall best outcome in pasture yield, quality and frequency and soil moisture and nutrient concentration. Application of P fertiliser with a moderate defoliation pressure to promote legume growth and N fixation has the potential to achieve multiple benefits in increasing pasture and livestock production and improving environmental sustainability in the alpine pasture of Qinghai-Tibet Plateau, a fragile and P-deficient ecosystem zone in China and its western neighbouring countries.
authors.affiliation: College of Grassland Science, Gansu Agricultural University, Lanzhou, Gansu, People's Republic of China.
authors.forename: Juan
authors.initials: J
authors.lastname: Qi
authors.affiliation: College of Grassland Science, Gansu Agricultural University, Lanzhou, Gansu, People's Republic of China; Department of Economic Development, Jobs, Transport and Resources, Hamilton, Victoria, Australia.
authors.forename: Zhongnan
authors.initials: Z
authors.lastname: Nie
authors.affiliation: College of Grassland Science, Gansu Agricultural University, Lanzhou, Gansu, People's Republic of China.
authors.forename: Ting
authors.initials: T
authors.lastname: Jiao
authors.affiliation: College of Grassland Science, Gansu Agricultural University, Lanzhou, Gansu, People's Republic of China.
authors.forename: Degang
authors.initials: D
authors.lastname: Zhang
mesh_terms: D002681:China; D017753:Ecosystem; D010758:Phosphorus / Q000737:chemistry*; D063245:Plant Development; D010944:Plants / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil; D010758:Phosphorus