TY - JOUR
T1 - Organic amendment additions to rangelands
T2 - A meta-analysis of multiple ecosystem outcomes
AU - Gravuer, Kelly
AU - Gennet, Sasha
AU - Throop, Heather L.
N1 - Funding Information:
We thank Wolfgang Viechtbauer for assistance in calculating confidence intervals for rma.mv model predictions based on multimodel averaging and three anonymous reviewers for their insightful comments on previous manuscript versions. Funding was provided by a NatureNet Science Fellowship to KG, with contributions from The Nature Conservancy, the Center for Biodiversity Outcomes at Arizona State University, and US National Science Foundation grant DEB 0953864 to HT. This research was conducted in collaboration with the Managing Soil Carbon working group supported by Science for Nature and People Partnership (SNAPP), a partnership of The Nature Conservancy, the Wildlife Conservation Society, and the National Center for Ecological Analysis and Synthesis (NCEAS) at the University of California, Santa Barbara.
Publisher Copyright:
© 2018 The Authors. Global Change Biology Published by John Wiley & Sons Ltd
PY - 2019/3
Y1 - 2019/3
N2 - Interest in land application of organic amendments—such as biosolids, composts, and manures—is growing due to their potential to increase soil carbon and help mitigate climate change, as well as to support soil health and regenerative agriculture. While organic amendments are predominantly applied to croplands, their application is increasingly proposed on relatively arid rangelands that do not typically receive fertilizers or other inputs, creating unique concerns for outcomes such as native plant diversity and water quality. To maximize environmental benefits and minimize potential harms, we must understand how soil, water, and plant communities respond to particular amendments and site conditions. We conducted a global meta-analysis of 92 studies in which organic amendments had been added to arid, semiarid, or Mediterranean rangelands. We found that organic amendments, on average, provide some environmental benefits (increased soil carbon, soil water holding capacity, aboveground net primary productivity, and plant tissue nitrogen; decreased runoff quantity), as well as some environmental harms (increased concentrations of soil lead, runoff nitrate, and runoff phosphorus; increased soil CO 2 emissions). Published data were inadequate to fully assess impacts to native plant communities. In our models, adding higher amounts of amendment benefitted four outcomes and harmed two outcomes, whereas adding amendments with higher nitrogen concentrations benefitted two outcomes and harmed four outcomes. This suggests that trade-offs among outcomes are inevitable; however, applying low-N amendments was consistent with both maximizing benefits and minimizing harms. Short study time frames (median 1–2 years), limited geographic scope, and, for some outcomes, few published studies limit longer-term inferences from these models. Nevertheless, they provide a starting point to develop site-specific amendment application strategies aimed toward realizing the potential of this practice to contribute to climate change mitigation while minimizing negative impacts on other environmental goals.
AB - Interest in land application of organic amendments—such as biosolids, composts, and manures—is growing due to their potential to increase soil carbon and help mitigate climate change, as well as to support soil health and regenerative agriculture. While organic amendments are predominantly applied to croplands, their application is increasingly proposed on relatively arid rangelands that do not typically receive fertilizers or other inputs, creating unique concerns for outcomes such as native plant diversity and water quality. To maximize environmental benefits and minimize potential harms, we must understand how soil, water, and plant communities respond to particular amendments and site conditions. We conducted a global meta-analysis of 92 studies in which organic amendments had been added to arid, semiarid, or Mediterranean rangelands. We found that organic amendments, on average, provide some environmental benefits (increased soil carbon, soil water holding capacity, aboveground net primary productivity, and plant tissue nitrogen; decreased runoff quantity), as well as some environmental harms (increased concentrations of soil lead, runoff nitrate, and runoff phosphorus; increased soil CO 2 emissions). Published data were inadequate to fully assess impacts to native plant communities. In our models, adding higher amounts of amendment benefitted four outcomes and harmed two outcomes, whereas adding amendments with higher nitrogen concentrations benefitted two outcomes and harmed four outcomes. This suggests that trade-offs among outcomes are inevitable; however, applying low-N amendments was consistent with both maximizing benefits and minimizing harms. Short study time frames (median 1–2 years), limited geographic scope, and, for some outcomes, few published studies limit longer-term inferences from these models. Nevertheless, they provide a starting point to develop site-specific amendment application strategies aimed toward realizing the potential of this practice to contribute to climate change mitigation while minimizing negative impacts on other environmental goals.
KW - arid
KW - biodiversity
KW - biosolids
KW - climate change
KW - compost
KW - ecosystem services
KW - grassland
KW - runoff
KW - savanna
KW - soil carbon
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U2 - 10.1111/gcb.14535
DO - 10.1111/gcb.14535
M3 - Article
C2 - 30604474
AN - SCOPUS:85059447387
SN - 1354-1013
VL - 25
SP - 1152
EP - 1170
JO - Global change biology
JF - Global change biology
IS - 3
ER -