Main authors: Zhanguo Bai, Thomas Casparia, Maria Ruiperez Gonzalez, Niels H. Batjes, Paul Mäder, Else K. Bünemann, Ron de Goede, Lijbert Brussaard, Minggang Xu, Carla Sofia Santos Ferreira, Endla Reintam, Hongzhu Fan, Rok Mihelič, Matjaž Glavan, Zoltán Tóth
iSQAPERiS editor: Jane Brandt
Source document: Bai, Z. et al. (2018) Effects of agricultural management practices on soil quality: a review of long-term experiments in Europe and China. Agriculture Ecosystems and Environment, 265, pp 1–7

 

Our study has confirmed that land management practices influence soil quality indicators in various ways. There are clear trends and relative changes in the five indicators as determined by the four-paired practices. However, the magnitude of the trends and direction of the indicator changes vary with the different management practices.

Several management practices had negative effects on soil quality indicators. For example, yield levels were lower under organic farming as compared to conventional farming and, to a lesser extent, no-tillage compared to conventional tillage. However, the yield reduction could be marginal, if other principles of conservation agriculture such as proper residue management and crop rotation are applied.

Conversely, there are also positive aspects under organic farming such as higher marketing price and reduced environmental damages. Therefore, to evaluate whether it is judicious to convert conventional farming to organic farming, socio-economic aspects will have to be considered in combination with soil quality impacts.

Most sensitive indicators

Under the framework chosen, earthworm numbers appear to be the most sensitive indicator for the four paired management practices and positively affected by all the promising practices in comparison to the corresponding standard practices. SOM content responds positively to all the promising practices in comparison to the references. Aggregate stability and yield are less sensitive to the practices, and soil pH appears to be the least sensitive indicator.

The agricultural practices chosen (e.g. organic matter input) represent categories rather than specific treatments (e.g. addition of farmyard manure, compost, green manure, crop residue, or slurry). Although details on the various different treatments under those categories were documented in the literature review database, a full-blown meta-analysis was beyond the intention and scope of research performed for the iSQAPER project and current manuscript.

Recommendations

LTEs are an invaluable source of information and at the basis of understanding the mechanisms and magnitude of soil change. Given the ever increasing pressures on agricultural land, every effort possible should be undertaken to maintain, enhance, and connect existing LTEs, and where possible invest to extend their network.

Opposite to our hypothesis, the potential for deducing meaningful trends for soil quality indicators from agricultural management practices was restricted by using currently available LTE data as the only source of information. Main reasons are the large study area with its huge range of pedo-climatic conditions, and the heterogeneous setup of LTEs making comparison of data difficult or impossible. Efforts such as the systematic mapping of evidence relating to the impacts of agricultural management on SOC described by Haddaway et al. (2015) are promising and should be extended to collate data about other soil quality relevant indicators.

Finally, it should be noted that farmers often know very well which specific soil parameters are the most relevant for their particular situation. Therefore, the view of land managers should be taken into account when evaluating various sets of indicators for soil quality (Lima et al., 2013; Palm et al., 2014), necessitating a transdisciplinary and participatory approach.

 


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