Abstract
In recent years, special attention has been given to the long-term effects of biochar on the performance of agro-ecosystems owing to its potential for improving soil fertility, harvested crop yields, and aboveground biomass production. The present experiment was set up to identify the effects on soil-plant systems of biochar produced more than 150 years ago in charcoal mound kiln sites in Wallonia (Belgium). Although the impacts of biochar on soil-plant systems are being increasingly discussed, a detailed monitoring of the crop dynamics throughout the growing season has not yet been well addressed. At present there is considerable interest in applying remote sensing for crop growth monitoring in order to improve sustainable agricultural practices. However, studies using high-resolution remote sensing data to focus on century-old biochar effects are not yet available. For the first time, the impacts of century-old biochar on crop growth were investigated at canopy level using high-resolution airborne remote sensing data over a cultivated field. High-resolution RGB, multispectral and thermal sensors mounted on unmanned aerial vehicles (UAVs) were used to generate high frequency remote sensing information on the crop dynamics. UAVs were flown over 11 century-old charcoal-enriched soil patches and the adjacent reference soils of a chicory field. We retrieved crucial crop parameters such as canopy cover, vegetation indices and crop water stress from the UAV imageries. In addition, our study also provides in-situ measurements of soil properties and crop traits. Both UAV-based RGB imagery and in-situ measurements demonstrated that the presence of century-old biochar significantly improved chicory canopy cover, with greater leaf lengths in biochar patches. Weighted difference vegetation index imagery showed a negative influence of biochar presence on plant greenness at the end of the growing season. Chicory crop stress was significantly increased by biochar presence, whereas the harvested crop yield was not affected. The main significant variations observed between reference and century-old biochar patches using in situ measurements of crop traits concerned leaf length. Hence, the output from the present study will be of great interest to help developing climate-smart agriculture practices allowing for adaptation and mitigation to climate.
Highlights
In the context of mitigating climate change and adapting to the loss of soil fertility, the application of biochar has been promoted during the last decades as a strategy for sustainably improving the soil hydric status and organic matter contents (e.g. Sohi et al, 2010; Malghani et al, 2013; Stewart et al, 2013; Kerré et al, 2017)
The biochar-enriched sites were found to be characterized by significantly higher soil organic carbon (SOC) and nitrogen contents (Fig. 3a), which was reported by Biederman and Stanley Harpole (2013) and de la Rosa et al (2014)
This paper presented a proof of concept of using unmanned aerial vehicles (UAVs)-based imageries in evaluating the effects of century-old biochar on crop growth and crop water stress in combination with in situ and laboratory measurements
Summary
In the context of mitigating climate change and adapting to the loss of soil fertility, the application of biochar has been promoted during the last decades as a strategy for sustainably improving the soil hydric status and organic matter contents (e.g. Sohi et al, 2010; Malghani et al, 2013; Stewart et al, 2013; Kerré et al, 2017). Yamato et al, 2006; Montanarella and Lugato, 2013; Lehmann and Joseph, 2015; Trupiano et al, 2017). Biochar can be obtained from a broad range of feedstocks including manure, wood, and crop residues (Trupiano et al, 2017). Many efforts have been devoted to providing an indication of the fresh biochar effect on soil properties such as soil acidity, nutrient retention, and water holding capacity (Biederman and Stanley Harpole, 2013; Lehmann et al, 2003; Glaser et al, 2002). De la Rosa et al (2014) showed that there is a strong positive relationship between the amount of biochar application and soil water holding capacity (WHC) by studying four types of biochar originating from different feedstocks. De la Rosa et al (2014) showed that there is a strong positive relationship between the amount of biochar application and soil water holding capacity (WHC) by studying four types of biochar originating from different feedstocks. Glaser et al (2002) reported that the WHC in terra
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