The potential of biochar in improving drainage, aeration and maize yields in heavy clay soils

Abstract

Heavy clay soils are globally widespread but their poor drainage and poor aeration limit their use for agriculture. This study was designed to test the effect of the amendment of biochar (BC) from woody shrubs on drainage/saturated hydraulic conductivity (Ksat), soil aeration/air capacity, available water capacity and biomass and grain yields of maize. In a field experiment, BC from Gliricidia sepium was applied in planting basins or rip lines at 2.5% and 5% w/w in addition to a control without BC. The maize biomass and grain yields were higher in BC treated plots compared to control (p<0.05) during the 2012 and 2013 seasons. There was no significant difference in the yields between 2.5% and 5% BC treatments (e.g. grain yield were 6.6 and 8.1 t ha-1 in 2012 and 9.3 and 10.3 t ha-1 in 2013 compared to control with 4.2 and 6.7 t ha-1 in 2012 and 2013, respectively). Soil from the same field site was also mixed with a similar woody shrub BC from Eupatorium adenophorum in the laboratory at rates of 2.5%, 5% and 10% BC w/w and a control without BC. The mixtures were then incubated and subjected to two wet-dry cycles for two weeks. Core samples were taken from the incubated soil and tested for bulk density, Ksat and pF measurements. Total porosity and moisture at field capacity and wilting point were 72.3%, 43.7% and 23.7%, respectively, and not affected by BC amendment (p>0.05). In contrast, bulk density decreased linearly by 0.011±0.002 g cm-3 per percent BC added (p<0.001). Ksat and air capacity of the soil were 288 cm day-1 and 30.9%, respectively falling within the generally accepted optimal range. Both Ksat and air capacity followed a significant quadratic relation (p<0.05) upon BC addition, decreasing at low BC doses, reaching a minimum at 3–5% BC and increasing at higher doses. Results allowed a partial attribution of the yield increases to changes in soil physical properties such as changes in bulk density and not clearly to Ksat and air capacity.

Prospects of Bioenergy Cropping Systems for A More Social-Ecologically Sound Bioeconomy

“…The cultivation of industrial crops in sites with high proportions of clay (>30%) [215] is promising because heavy clay is more or less unsuitable for the cultivation of food crops due to adverse rooting conditions [216]. This means that the potential for land use conflicts between industrial crop and food crop cultivation would be low.…”

Role of biochar in managing the irrigation water requirements of maize plants: the pyramid model signifying the soil hydro-physical and environmental markers

“…In the clayey soil, the high content of clay particles probably affect soil characteristics directly and indirectly (Sarkar et al, 2018), causing soil compaction (Churchman, 2018) and probably arising many potential problems, e.g. low infiltration rates (Alaoui et al, 2018) beside of poor drainage and aeration conditions (Obia et al, 2018). To improve such characteristics, biochar application is recommended because of its low density, highly porous structure and grain sized distribution (Zhou et al, 2018).…”

“…This amendment may rearrange the inter-aggregate pore spaces (Villagra-Mendoza and Horn, 2018) and consequently improve soil physical properties, e.g. soil bulk density (Obia et al, 2018) and the stability of soil aggregates (Li et al, 2018). Moreover, it minimizes the potentiality of clayey soils towards degradation with either wind or water erosion (Churchman, 2018).…”

Biochar amendment increases soil microbial biomass and plant growth and suppresses Fusarium wilt in tomato

“…However, the reasons for changes in root growth are not well identified in existing studies, and they vary with the properties of biochar and soil characteristics in different environments (Lehmann et al 2011). Biochars with properties that improve soil chemical and physical characteristics, such as nutrient availability (Novak et al 2009), water retention (Bikbulatova et al 2018), pH (Chan et al 2008) and aeration (Obia et al 2018), are hypothesized as the most likely cause in increased root growth. These effects can also be interpreted as an indication of the better supply of soil resources with consequent improvement in plant nutrition.…”