Impact of biochar addition on water retention, nitrification and carbon dioxide evolution from two sandy loam soils

Abstract

Summary Some intensive agricultural practices result in soil degradation through loss of soil organic matter. Organic farming may mitigate this problem, if managed properly, but may result in a yield penalty compared with conventional systems. Biochar addition to soil could influence both agricultural systems, but previous studies are not definitive about its impact on soil processes. Sandy soils are more susceptible to the effects of reduced soil organic matter on soil hydrology and nutrient dynamics. Nitrogen (N) is important for crop growth and soil water content can influence its transformation and cycling. This study explored the effect of biochar amendment on soil water retention and nitrification processes in soils under organic and conventional management. Carbon dioxide evolution was used as an indicator of related microbial activity. A water release curve study and a 60‐day incubation experiment were set up to consider the effect of biochar application on organically and conventionally managed sandy loam soils. The results showed that addition of biochar increased water retention for both soils and this is attributed to its porous structure. On incubation of an organically managed soil, with green‐waste compost, initial ammonium level was small, reflecting microbial demand for N. The large cation exchange capacity of the organically managed soil retained ammonium, reducing availability for nitrification. Carbon dioxide evolution increased with continuing small contents of ammonium and nitrate when biochar was added to the organically managed soil. Biochar enhanced nitrification without increased respiration during incubation of a conventionally managed soil with added mineral N; a possible explanation for this enhancement is the increase in pH resulting from the biochar addition.

The response of some physiological traits of chickpea (Cicer arietinum L.)to biochar and phosphorus fertilizer application

“…The increase in stomatal conductance with biochar application was greater in the winter (drier) season compared to the summer (wetter) season probably due to the effect of biochar on soil moisture retention and plant available water (Glaser et al 2002). Similarly, stomatal conductance in tomatoes decreased in no biochar soils that easily dried out (Akhtar et al 2015), and in cowpea stomatal conductance was greater in soils having greater moisture content (Ulyett et al 2014). These effects of biochar on stomatal conductance were attributed to an increase in soil water holding capacity with biochar application; stomatal closure is usually the first line of defence against water stress.…”

Biochar Impacts Soil Microbial Community Composition and Nitrogen Cycling in an Acidic Soil Planted with Rape

“…As nitrification is an acidifying process, 42 alkaline biochar may create much more favorable conditions for nitrifiers thus increasing nitrification rates due to its liming effect. 43,44 The decreased N 2 O emission and increased nitrification rates demonstrate that the relative contribution of nitrification to N 2 O emissions is much less than that of denitrification (including nitrifier denitrification) in this soil. This result shows that biochar inhibition on nitrification is unlikely to be the mechanism of N 2 O reduction in the soil.…”

Behavior the Water in Typical Yellow Oxisoil of Central Amazon Under Biochar Application

“…At the higher doses (> 3% in the substrate -60 T ha -1 ) a stable water loss behavior was observed, with the lowest values being observed in all evaluated periods. The increase of the water retention in such conditions can be explained by the increase in the volume of water trapping points with the increase of the occupation in the solid phase of the soil, provoking, among others, the smaller leakage of water molecules through the pores (ULYETT et al al., 2014).…”

“…According to Abel et al (2013), the increase in the availability of water with the use of biochar is linked to a decrease in the soil density that ranged from 1.00 to 5.00%, which promotes the elevation of the number of soil pores and can be useful in soils with high tendency to compaction, such as ocurred in the Amazonian oxisoil and ultisoil. According to Ulyett et al (2014) and Hagemann et al (2016), the porous nature of biochar may influence the increase of water retention in soils, especially in sandy soils, which due to the presence of coarser granulometry, the loss of water is more pronounced.…”