The impact of mulch type on soil organic carbon and nitrogen pools in a sloping site

Three mulch treatments were tested for their ability to control erosion on a sloping site. Additionally, the choice of mulch can also enhance revegetation success and improve soil organic matter input. This study aimed to investigate the effects of three mulching treatments, hydro-seeding, granite mulch and forest mulch, on soil C and N pools at different positions on highly erodible slope with approximately 30 % gradient. Soil moisture, total C (TC), total N (TN), hot water-extractable organic C (HWEOC), hot water-extractable total N (HWETN), microbial biomass C and N (MBC and MBN), inorganic N and potentially mineralisable N were measured. All variables were significantly higher in soils amended with forest mulch than those with hydro-seeding and granite mulch, for the same slope positions. Soil moisture was significantly higher in the lower slope position than middle and upper slope positions in hydro-seeding and granite mulch treatments, whereas no slope effect was observed on soil moisture under the forest mulch application. In the forest mulch treatment, the upper slope position had higher soil TC, TN, HWEOC, HWETN, MBC, MBN, NO3--N and total inorganic N than the middle and lower slope positions. Five years following mulch application, forest mulch still exerted a significant influence on soil fertility compared to the other treatments and the influence on soil moisture suggests that this treatment would be the most effective in the control of water-driven soil erosion on this steep site. © 2013 Springer-Verlag Berlin Heidelberg

Physiological traits of Acacia concurrens and Eucalyptus crebra with respect to radical site preparation practices in a revegetation trial, south east Queensland, Australia

Purpose: To successfully establish revegetation, there is a need for weed control. Herbicide application and top soil removal (scalping) may be used to suppress weeds. However, scalping alters soil water and nitrogen availability which in turn may affect plant physiology and performance during the early phase of establishment. Materials and methods: A field trial was established in south east Queensland, Australia, to examine weed control methods, including herbicide application and scalping. Plant survival, mean periodic height gain, specific leaf area and leaf-level physiological traits were measured for Acacia concurrens Pedley and Eucalyptus crebra F. Muell. for 17 months following tree establishment. Results and discussion: Plant survival and growth of A. concurrens were superior in the scalped area compared to the herbicide area, whereas neither survival nor growth of E. crebra was influenced by weed control methods. In general, there were no or little effect of site preparation practices on carbon and nitrogen isotope composition, specific leaf area, photosynthesis, maximum photosynthesis and instantaneous water-use efficiency. Photosynthetic capacity was not influenced by site preparation practices as reflected through the maximum rate of carboxylation and maximum rate of electron transport. Conclusions: Despite altering soil nutrient availability in the scalped areas and high weed coverage in the herbicide areas, there was no substantial alteration in plant physiology for both species. E. crebra was less affected by either low nutrient availability in the scalped areas or high weed coverage in the herbicide areas compared to A. concurrens. Therefore, E. crebra could be considered as a valuable species to revegetate degraded lands. © 2014 Springer-Verlag Berlin Heidelberg