Biochar soil amendment as a solution to prevent Cd-tainted rice from China: Results from a cross-site field experiment

AbstractCowpea, a food and nutrition security crop is being threatened by decline in soil fertility especially in small holder farmstead. The natural arbuscular mycorrhizal fungi in the soil could improve its ability to acquire and retain nutrients thereby leading to higher yield. This irrigated field research was conducted to determine the effect of biochar rates and cropping systems on selected soil chemical properties, soil microbial biomass carbon (SMBC), nitrogen (SMBN), phosphorus (SMBP), and vesicular-arbuscular mycorrhizal (VAM) spore count and mycorrhizal fungi colonization (AMF) of cowpea. Experimental design was 3 x 3 factorial in randomized complete block design (RCBD). Factor A was three cropping systems; sole cowpea, intercropping and intra-cropping, while factor B was three biochar rates; control (biochar at 0 t ha-1 (B0)), biochar at 2.5 t ha-1 (B1) and biochar at 5 t ha-1 (B2). These were replicated in three blocks to constitute 27 plots. The entire plot was cleared, ploughed and demarcated into beds with hoes and diggers. Cowpea sole or inter- or intra- cropped with maize were planted in a spacing distance of 25cm by 75cm, with intercropped cowpea being in-between the interrow spacing (75 cm), while the intracropped cowpeas was planted between the intrarow spacing (25 cm). Biochar soil amendment were applied two weeks after planting by making a groove in-between the rows in the soil and covering them with soil. The result showed that biochar soil amendment and interaction of biochar with cropping system significantly (p<0.05) affected SMBN, SMBC, total&#160; VAM spore count and AMF colonization by cowpea, whereas cropping system significantly affected only total VAM spore count and AMF colonization by cowpea. B2 amended soil had the highest SMBC content (0.028 mg kg-1) while the least was from control plot (0.021 mg kg -1), SMBN was highest in B1 amended soil (0.004 mg kg-1), followed by control plot (0.002 mg kg-1). Control had higher AMF and total VAM spore count while biochar amended soil had higher soil microbial properties. Considering the cropping systems, inter and intra-cropping had higher microbial biomass and total VAM spore count than sole cowpea whereas sole cowpea had higher AMF infection of cowpea than the intercropped cowpea. Biochar at 5 tha-1 had the highest available P. Generally, this study showed superiority of the interaction of biochar with cropping systems over sole cropping in the improvement of soil properties in degraded soils of North-West province of South Africa.Key words: Cropping systems; Chromic Luvisol; Microbial properties; Soil fertility; Soil amendment

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The Biochar challenge in Mediterranean viticulture: results from 10 years of field experiment

10.5194/egusphere-egu2020-20731 ◽

2020 ◽

Author(s):

Silvia Baronti ◽

Anita Maienza ◽

Fabrizio Ungaro ◽

Antonio,Antonello Montagnoli ◽

Lorenzo Genesio ◽

...

Keyword(s):

Climate Change ◽

Field Experiment ◽

Water Relations ◽

Soil Amendment ◽

Field Experiments ◽

Central Italy ◽

Plant Water ◽

Grape Quality ◽

Mediterranean Countries

There are extensive reports and scientific articles in literature on the applicability of biochar as soil amendment in agriculture and on the benefits that this practice can bring in terms of soil improvement and optimization of water resources. The use of biochar as a soil amendment in agriculture is a suitable option that helps to mitigate the effects of climate change. Biochar has an approximate mean residence time in the soil over 1,000 years and this long-term stability is a fundamental prerequisite for considering biochar as a suitable method for carbon sequestration. Unfortunately, most literature provides results based on one-year trials. Not enough for a soil amendment to be able to claim effectiveness for many decades and not enough for a soil treatment to be considered irreversible. An effective option to fill this knowledge gap is represented by long-term field experiments. In this study, we investigated the effect of biochar application on plant water relations and soil properties during 10 years in a field experiment in Central Italy on Vitis vinifera. Biochar was applied at a rate of 22 t ha-1 in two consecutive growing seasons: 2009 and 2010. The results obtained during these years on biochar treatment compared to the control treatment are exciting: we demonstrated an increase in grape production, up to 66%, without a decrease of the grape quality, an increase in plant-soil water relations, no effects on the concentrations of soil PAHs, no eco-toxicity soil effect and a positive effect on soil chemical and biological parameters. Surprisingly, after 10 years the biochar effect continued to demonstrate significant differences among treatments, in particular: a significant increase of soil biological quality, decrease in soil bulk density coupled with a corresponding increase in saturated hydraulic conductivity, an enhance in soil available water content and a significant improvement of plant water status. The modification of plant water availability induced by biochar application increase the resilience of vineyards to droughts, as demonstrated by the lower leaf potential and higher stomatal conductance. This effect has a significant impact on quantity and quality of grape production after 10 years. Moreover, in the long-term perspective the biochar demonstrates to have an effect on soil biological communities that resulted sensitive to biochar with positive increase of abundance of species related to soil moisture content and enhance of biodiversity index. According to these results, the viticulture is now in the position to provide an effective contribution to mitigate climate change and we expect that this will be an example for other Mediterranean countries.

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