A pinboard by
Muhammad Riaz

Department of Environmental Sciences, Government College University Faisalabad Pakistan


Sustainable crop production, carbon sequestration and greenhouse gas emissions under climate change

Healthy soils are pre-requisite to meeting food security for ever-increasing human population especially in the developing countries. Managing soil organic matter is first step of keeping healthy agro-ecosystems. Agricultural crop production in developing countries including Pakistan is generally hampered by constraints of multiple origins leading to poor economic returns and, hence, below-par living standards of small-holding farming communities. Therefore, there is an urgent need of revisiting current soil and crop management practices to cope with climate change and meet food security.

Use of organic amendments is considered a practical approach under such compelling scenarios. Biochar, a product of biomass pyrolysis under no or limited supply of oxygen, is gaining popularity as an innovative approach for biomass waste management and development of climate-smart soil-plant systems. Biochar improves soil nutrient holding capacities, water retention and mitigating greenhouse gas emissions. Evident from various success stories on global scale, biochar has gained popularity at very fast rate especially, in developing countries. Since biochar is recalcitrant to decomposition, it stays in the soil-plant systems on scale ranging from centuries to millennia, providing multiple benefits including carbon sequestration and encouraging sustainable crop production.

Initial research in Pakistan under my supervision has very promising results and helped farmers boosting their farm income and economic returns by adopting biochar technology at farm-scale levels. They have benefited multiple ways by integrating biochar in farm management practices in terms of increasing soil carbon stocks, deceasing soil degradation and erosion, reducing fertilizer losses to environment by increasing fertilizer use efficiency, decreasing greenhouse gas emissions, and ultimately, maintaining healthy soils.

My research focuses on the use of biochar as low cost technology to develop climate smart-agriculture for resource-poor and small landholder farmers. Results from my research from Farmers' Participatory Field Trails has show that, if optimized, biochar can revolutionized crop cultivation and help millions in developing countries involved in subsistence farming to improve farm income and food scurrility.


Biochar and hydrochar effects on greenhouse gas (carbon dioxide, nitrous oxide, and methane) fluxes from soils.

Abstract: With a growing world population and global warming, we are challenged to increase food production while reducing greenhouse gas (GHG) emissions. We studied the effects of biochar (BC) and hydrochar (HC) produced via pyrolysis or hydrothermal carbonization, respectively, on GHG fluxes in three laboratory incubation studies. In the first experiment, ryegrass was grown in sandy loam mixed with equal amounts of a nitrogen-rich peanut hull BC, compost, BC+compost, double compost, or no addition (control); wetting-drying cycles and N fertilization were applied. Biochar with or without compost significantly reduced NO emissions and did not change the CH uptake, whereas ryegrass yield was significantly increased. In the second experiment, 0% (control) or 8% (w/w) of BC (peanut hull, maize, wood chip, or charcoal) or 8% HC (beet chips or bark) was mixed into a soil and incubated at 65% water-holding capacity (WHC) for 140 d. Treatments included simulated plowing and N fertilization. All BCs reduced NO emissions by ∼60%. Hydrochars reduced NO emissions only initially but significantly increased them after N fertilization to 302% (HC-beet) and 155% (HC-bark) of the control emissions, respectively. Large HC-associated CO emissions suggested that microbial activity was stimulated and that HC was less stable than BC. In the third experiment, nutrient-rich peanut hull BC addition and incubation over 1.5 yr at high WHCs did not promote NO emissions. However, NO emissions were significantly increased with BC after NHNO addition. In conclusion, BC reduced NO emissions and improved the GHG-to-yield ratio under field-relevant conditions. However, the risk of increased NO emissions with HC addition must be carefully evaluated.

Pub.: 04 Jul '12, Pinned: 26 Aug '17

Interactions between biochar and mycorrhizal fungi in a water-stressed agricultural soil

Abstract: Biochar may alleviate plant water stress in association with arbuscular mycorrhizal (AM) fungi but research has not been conclusive. Therefore, a glasshouse experiment was conducted to understand how interactions between AM fungi and plants respond to biochar application under water-stressed conditions. A twin chamber pot system was used to determine whether a woody biochar increased root colonisation by a natural AM fungal population in a pasture soil (‘field’ chamber) and whether this was associated with increased growth of extraradical AM fungal hyphae detected by plants growing in an adjacent (‘bait’) chamber containing irradiated soil. The two chambers were separated by a mesh that excluded roots. Subterranean clover was grown with and without water stress and harvested after 35, 49 and 63 days from each chamber. When biochar was applied to the field chamber under water-stressed conditions, shoot mass increased in parallel with mycorrhizal colonisation, extraradical hyphal length and shoot phosphorus concentration. AM fungal colonisation of roots in the bait chamber indicated an increase in extraradical mycorrhizal hyphae in the field chamber. Biochar had little effect on AM fungi or plant growth under well-watered conditions. The biochar-induced increase in mycorrhizal colonisation was associated with increased growth of extraradical AM fungal hyphae in the pasture soil under water-stressed conditions.

Pub.: 11 Apr '16, Pinned: 26 Aug '17

Benefits of biochar, compost and biochar-compost for soil quality, maize yield and greenhouse gas emissions in a tropical agricultural soil.

Abstract: Soil quality decline represents a significant constraint on the productivity and sustainability of agriculture in the tropics. In this study, the influence of biochar, compost and mixtures of the two on soil fertility, maize yield and greenhouse gas (GHG) emissions was investigated in a tropical Ferralsol. The treatments were: 1) control with business as usual fertilizer (F); 2) 10 t ha(-1) biochar (B)+F; 3) 25 t ha(-1) compost (Com)+F; 4) 2.5 t ha(-1) B+25 t ha(-1) Com mixed on site+F; and 5) 25 t ha(-1) co-composted biochar-compost (COMBI)+F. Total aboveground biomass and maize yield were significantly improved relative to the control for all organic amendments, with increases in grain yield between 10 and 29%. Some plant parameters such as leaf chlorophyll were significantly increased by the organic treatments. Significant differences were observed among treatments for the δ(15)N and δ(13)C contents of kernels. Soil physicochemical properties including soil water content (SWC), total soil organic carbon (SOC), total nitrogen (N), available phosphorus (P), nitrate-nitrogen (NO3(-)N), ammonium-nitrogen (NH4(+)-N), exchangeable cations and cation exchange capacity (CEC) were significantly increased by the organic amendments. Maize grain yield was correlated positively with total biomass, leaf chlorophyll, foliar N and P content, SOC and SWC. Emissions of CO2 and N2O were higher from the organic-amended soils than from the fertilizer-only control. However, N2O emissions generally decreased over time for all treatments and emission from the biochar was lower compared to other treatments. Our study concludes that the biochar and biochar-compost-based soil management approaches can improve SOC, soil nutrient status and SWC, and maize yield and may help mitigate greenhouse gas emissions in certain systems.

Pub.: 23 Nov '15, Pinned: 26 Aug '17

Biochar as a global change adaptation: predicting biochar impacts on crop productivity and soil quality for a tropical soil with the Environmental Policy Integrated Climate (EPIC) model

Abstract: The Environmental Policy Integrated Climate (EPIC) model with newly-developed biochar algorithms was used to determine the impacts of biochar amendments on corn (Zea mays L.) yields, soil cation exchange capacity (CEC), pH, bulk density (Db) and soil organic carbon (SOC) dynamics. The objectives were (1) to determine biochar impacts on crop yields and soil properties of a tropical soil and (2) to evaluate biochar’s potential as a climate change adaptation tool. EPIC was validated using results of a 4−yr experiment performed on an Amazonian Oxisol amended with biochar at rates of 0, 8, and 20 Mg ha−1. Simulated yields of corn on biochar amended soil were significantly greater than control yields (p < 0.05). Simulated soil pH increased from original 3.9 to 4.19, CEC increased from 9.76 to 11.5 cmolc kg−1, and SOC also increased. After validation, EPIC was used to simulate the impacts of the same biochar rates applied at 4 year intervals on corn yields and soil properties over the next 20 years. Soil CEC increased from 11.1 cmolc kg−1 to 20.2 cmolc kg−1 for the highest biochar application rate. Soil pH increased from 3.9 to 5.64. SOC increased up to 2.59 % for the highest biochar application rate with decreased topsoil Db from 1.11 Mg m−3 to 0.97 Mg m−3. Long-term corn yields were slightly decreased. Although the results are biochar-, dose-, and soil-specific, biochar additions to tropical soils hold promise as a climate change adaptation tool resulting in increased soil carbon sequestration and improved soil properties.

Pub.: 18 Mar '14, Pinned: 26 Aug '17

Plant growth responses to biochar addition: an Australian soils perspective

Abstract: The use of biochar as an agricultural amendment has attracted much attention owing to its potential to improve soil condition and plant growth; however, production outcomes are often uncertain. Although soil type is a major driver of plant productivity, there are relatively few biochar studies that directly compare plant growth responses across a range of soil types. We tested the wheat growth response to biochar derived from poultry litter and from wheat straw applied at 1, 5 and 10 t ha−1 (approximately 0.13, 0.67 and 1.33 % w/w) in four soils representing major agricultural regions in Australia: an acidic arenosol (Western Australian cereal belt), an acidic rhodic ferralsol (Northern New South Wales), a neutral vertisol (Queensland cropping) and an alkaline haplic calcisol (Eyre Peninsula in South Australia). In the neutral vertisol, where plant growth was vigorous in the control treatments, biochar had little impact, whereas in the alkaline calcisol, there was a small significant increase in shoot biomass at high (10 t ha−1) application rates. Plant growth responses in the acidic soils were most evident but demonstrated a strong contrast to one another. In the acidic arenosol, negative growth impact correlated with increasing electrical conductivity, while in the acidic ferralsol a small rate-dependent increase in pH correlated with relatively large gains in biomass, possibly due to improved phosphorus nutrition and alleviated Al toxicity. Moving towards effective integration of biochar as a management tool will not only require stratification based on soil types, but wider consideration of the main plant production constraints, such as pH, pertinent to a particular system.

Pub.: 13 May '14, Pinned: 26 Aug '17

Does biochar influence soil physical properties and soil water availability?

Abstract: This study aims to (i) determine the effects of incorporating 47 Mg ha−1 acacia green waste biochar on soil physical properties and water relations, and (ii) to explore the different mechanisms by which biochar influences soil porosity.The pore size distribution of the biochar was determined by scanning electron microscope and mercury porosimetry. Soil physical properties and water relations were determined by in situ tension infiltrometers, desorption and evaporative flux on intact cores, pressure chamber analysis at −1,500 kPa, and wet aggregate sieving.Thirty months after incorporation, biochar application had no significant effect on soil moisture content, drainable porosity between –1.0 and −10 kPa, field capacity, plant available water capacity, the van Genuchten soil water retention parameters, aggregate stability, nor the permanent wilting point. However, the biochar-amended soil had significantly higher near-saturated hydraulic conductivity, soil water content at −0.1 kPa, and significantly lower bulk density than the unamended control. Differences were attributed to the formation of large macropores (>1,200 μm) resulting from greater earthworm burrowing in the biochar-amended soil.We found no evidence to suggest application of biochar influenced soil porosity by either direct pore contribution, creation of accommodation pores, or improved aggregate stability.

Pub.: 08 Dec '13, Pinned: 26 Aug '17

Effects of biochar amendments on soil microbial biomass and activity.

Abstract: Environmental benefits reported in the literature of using biochar as a soil amendment are generally increased microbial activity and reduced greenhouse gas (GHG) emissions. This study determined the effects of amendment with biomass feedstocks (spent coffee grounds, wood pellets, and horse bedding compost) and that of biochars (700°C) produced from these feedstocks on soil microbial biomass (C and N) and activity. Soils were amended with these substrates at 0.75% by weight and incubated for up to 175 d under laboratory conditions. Biochar residual effects on soil microbial activity were also studied by amending these soils with either ammonium nitrate (NHNO, 35 mg N kg) or with glucose (864 mg C kg) plus NHNO. Soil microbial biomass C and N, net N mineralization, and CO, NO, and CH emissions were measured. Amendment with biomass feedstocks significantly increased soil microbial biomass and activity, whereas amendment with the biochars had no significant effect. Also, biochar amendment had no significant effect on either net N mineralization or NO and CH emissions from soil. These results indicate that production of biochars at this high temperature eliminated potential substrates. Microbial biomass C in biochar-amended and unamended soils was not significantly different following additions of NHNO or glucose plus NHNO, suggesting that microbial access to otherwise labile C and N was not affected. This study shows that biochars produced at 700°C, regardless of feedstock source, do not enhance soil microbial biomass or activity.

Pub.: 21 Jan '15, Pinned: 26 Aug '17

Chemically and biologically-mediated fertilizing value of manure-derived biochar.

Abstract: This study evaluates the potential of manure-derived biochars in promoting plant growth and enhancing soil chemical and biological properties during a 150day pot experiment. Biochars from pyrolysis of poultry litter (PL) and swine manure (SM) at 400 and 600°C, and a commonly available wood chip (WC) biochar produced at high temperature (1000°C) were incorporated to silt-loam (SL) and sandy (SY) soils on a 2% dry soil weight basis. Ryegrass was sown and moisture was adjusted to 60% water filled pore space (WFPS). The PL400 and SM400 biochars significantly increased (p<0.05) shoot dry matter (DM) yields (SL soil) and enhanced nitrogen (N), phosphorus (P) and potassium (K) uptake by the plants in both soils, compared to the Control. All biochars significantly increased the soil carbon (C) contents compared to the Control. Total N contents were significantly greater for PL400 and PL600 treatments in both soils. The dehydrogenase activity (DA) significantly increased for PL400 and SM400 treatments and was positively correlated with the volatile matter (VM) contents of the biochars, while β-glucosidase activity (GA) decreased for the same treatments in both soils. All biochars significantly shifted (p≤0.05) the bacterial community structure compared to the Control. This study suggests that pyrolysis of animal manures can produce a biochar that acts as both soil amendment and an organic fertilizer as proven by increased NPK uptake, positive liming effect and high soil nutrient availability, while WC biochar could work only in combination with fertilizers (organic as well as mineral).

Pub.: 08 Feb '16, Pinned: 26 Aug '17

Hardwood biochar and manure co-application to a calcareous soil.

Abstract: Biochar may affect the mineralization rate of labile organic C sources such as manures via microbial community shifts, and subsequently affect nutrient release. In order to ascertain the positive or negative priming effect of biochar on manure, dairy manure (2% by wt.) and a hardwood-based, fast pyrolysis biochar were applied (0%, 1%, 2%, and 10% by wt.) to a calcareous soil. Destructive sampling occurred at 1, 2, 3, 4, 6 and 12 months to monitor for changes in soil chemistry, water content, microbial respiration, bacterial populations, and microbial community structure. Overall results showed that increasing biochar application rate improved the soil water content, which may be beneficial in limited irrigation or rainfall areas. Biochar application increased soil organic C content and plant-available Fe and Mn, while a synergistic biochar-manure effect increased plant-available Zn. Compared to the other rates, the 10% biochar application lowered concentrations of NO3-N; effects appeared masked at lower biochar rates due to manure application. Over time, soil NO3-N increased likely due to manure N mineralization, yet soil NO3-N in the 10% biochar rate remained lower as compared to other treatments. In the presence of manure, only the 10% biochar application caused subtle microbial community structure shifts by increasing the relative amounts of two fatty acids associated with Gram-negative bacteria and decreasing Gram-positive bacterial fatty acids, each by ∼1%. Our previous findings with biochar alone suggested an overall negative priming effect with increasing biochar application rates, yet when co-applied with manure the negative priming effect was eliminated.

Pub.: 27 May '15, Pinned: 26 Aug '17

Biochar and fertiliser applications influence phosphorus fractionation and wheat yield

Abstract: The use of biochar in agriculture to achieve the dual benefits of improving soil quality whilst sequestering carbon (C) has received much attention. However, in low-intensity broadacre agricultural systems where yield is constrained by rainfall and costs associated with phosphorus (P) fertiliser, the application of biochar at rates commonly reported (>10 t ha−1) are likely to be prohibitively expensive where yield benefits cannot be guaranteed. In marginal areas where calcareous soils dominate, biochar application has no liming effect, reducing its value compared to application in acidic soils. In the present study, we use a field experiment to investigate the interaction between P fertilisation and biochar banding at low application rates (<1 t ha−1) on wheat yield and soil P fractionation (assessed by a modified Hedley method) in a highly alkaline Haplic Calcisol in a dryland broadacre cropping system. Our results demonstrate no statistically significant effect of low rate biochar banding on wheat yield in this highly P-constrained soil, but a significant effect of both biochar and fertiliser on P fractionation in both years of the study. Higher P fertiliser rates significantly increased wheat yield in all biochar treatments. The interactions between biochar, P fertiliser and P fractionation indicate shifts in potential P availability both as a result of P fertilisation and also biochar application. Further work is required in low productivity calcareous systems such as that studied here to elucidate the potential for biochar amendment to improve productivity and sequester C.

Pub.: 13 Aug '13, Pinned: 26 Aug '17

Biochar affected by composting with farmyard manure.

Abstract: Biochar applications to soils can improve soil fertility by increasing the soil's cation exchange capacity (CEC) and nutrient retention. Because biochar amendment may occur with the applications of organic fertilizers, we tested to which extent composting with farmyard manure increases CEC and nutrient content of charcoal and gasification coke. Both types of biochar absorbed leachate generated during the composting process. As a result, the moisture content of gasification coke increased from 0.02 to 0.94 g g, and that of charcoal increased from 0.03 to 0.52 g g. With the leachate, the chars absorbed organic matter and nutrients, increasing contents of water-extractable organic carbon (gasification coke: from 0.09 to 7.00 g kg; charcoal: from 0.03 to 3.52 g kg), total soluble nitrogen (gasification coke: from not detected to 705.5 mg kg; charcoal: from 3.2 to 377.2 mg kg), plant-available phosphorus (gasification coke: from 351 to 635 mg kg; charcoal: from 44 to 190 mg kg), and plant-available potassium (gasification coke: from 6.0 to 15.3 g kg; charcoal: from 0.6 to 8.5 g kg). The potential CEC increased from 22.4 to 88.6 mmol kg for the gasification coke and from 20.8 to 39.0 mmol kg for the charcoal. There were little if any changes in the contents and patterns of benzene polycarboxylic acids of the biochars, suggesting that degradation of black carbon during the composting process was negligible. The surface area of the biochars declined during the composting process due to the clogging of micropores by sorbed compost-derived materials. Interactions with composting substrate thus enhance the nutrient loads but alter the surface properties of biochars.

Pub.: 16 May '13, Pinned: 26 Aug '17

Germination tests for assessing biochar quality.

Abstract: Definition, analysis, and certification of biochar quality are crucial to the agronomic acceptance of biochar. While most biochars have a positive impact on plant growth, some may have adverse effects due to the presence of phytotoxic compounds. Conversely, some biochars may have the ability to adsorb and neutralize natural phytotoxic compounds found in soil. We evaluated the effects of biochars on seedling growth and absorption of allelochemicals present in corn ( L.) residues. Corn seeds were germinated in aqueous extracts of six biochars produced from varied feedstocks, thermochemical processes, and temperatures. Percent germination and shoot and radicle lengths were evaluated at the end of the germination period. Extracts from the six biochars had no effect on percent germination; however, extracts from three biochars produced at high conversion temperatures significantly inhibited shoot growth by an average of 16% relative to deionized (DI) water. Polycyclic aromatic hydrocarbons detected in the aqueous extracts are believed to be at least partly responsible for the reduction in seedling growth. Repeated leaching of biochars before extract preparation eliminated the negative effects on seedling growth. Biochars differ significantly in their capacity to adsorb allelochemicals present in corn residues. Germination of corn seeds in extracts of corn residue showed 94% suppression of radicle growth compared to those exposed to DI water; however, incubation of corn residue extracts with leached biochar for 24 h before initiating the germination test increased radicle length 6 to 12 times compared to the corn residue extract treatments. Germination tests appear to be a reliable procedure to differentiate between effects of different types of biochar on corn seedling growth.

Pub.: 04 Jul '12, Pinned: 26 Aug '17

Characterization of biochar and its effects on the water holding capacity of loamy sand soil: Comparison of hemlock biochar and switchblade grass biochar characteristics

Abstract: Two of the most important resources in agriculture are soil and water. The quality of the soil determines the health and output of crops. Biochar has been recognized as being a useful soil amendment due to its perceived benefits of increasing water and nutrient retention. However, limited research has been conducted to compare the characteristics of biochar created from different feedstocks to determine which are the most effective at raising water holding capacity. This study compared the water holding capacity and chemical composition of biochar created from two different materials: eastern hemlock and switchblade grass. Results showed that both the hemlock char and switchblade grass char were able to significantly raise the water holding capacity of loamy sand. The switchblade grass increased the water holding capacity more than the hemlock biochar. For example, at a mixture rate of 10% biochar by weight, switchblade grass increased loamy sand's water holding capacity by 228%, compared with 133% for hemlock. The water holding capacity of the switchblade grass biochar alone was 448.69% of its weight and the hemlock biochar held 268.34% of its weight. These results suggest that switchblade grass may be better suited for improving water retention in sandy soils. © 2017 American Institute of Chemical Engineers Environ Prog, 2017

Pub.: 17 Mar '17, Pinned: 26 Aug '17

Biochar-Induced Changes in Soil Resilience: Effects of Soil Texture and Biochar Dosage

Abstract: Biochars are, amongst other available amendment materials, considered as an attractive tool in agriculture for carbon sequestration and improvement of soil functions. The latter is widely discussed as a consequence of improved physical quality of the amended soil. However, the mechanisms for this improvement are still poorly understood. This study investigated the effect of woodchip biochar amendment on micro-structural development, micro- and macro-structural stability, and resilience of two differently textured soils, fine sand (FS) and sandy loam (SL). Test substrates were prepared by adding 50 or 100 g kg−1 biochar to FS or SL. Total porosity and plant available water were significantly increased in both soils. Moreover, compressive strength of the aggregates was significantly decreased when biochar amount was doubled. Mechanical resilience of the aggregates at both micro- and macro-scale was improved in the biochar-amended soils, impacting the cohesion and compressive behavior. A combination of these effects will result in an improved pore structure and aeration. Consequently, the physicochemical environment for plants and microbes is improved. Furthermore, the improved stability properties will result in better capacity of the biochar-amended soil to recover from the myriad of mechanical stresses imposed under arable systems, including vehicle traffic, to the weight of overburden soil. However, it was noted that doubling the amendment rate did not in any case offer any remarkable additional improvement in these properties, suggesting a further need to investigate the optimal amendment rate.

Pub.: 03 Mar '17, Pinned: 26 Aug '17

Biochar from Biomass and Waste

Abstract: There is an increasing realisation that biomass and organic wastes are valuable feedstocks for second generation biorefining processes that give rise to platform chemicals to substitute for dwindling petrochemical resources, and for pyrolysis processes that produce syngas, bio-oil, and biochar from biomass, organic wastes, and the biorefining residuals of the future. The experimental work described has focused on physical properties and compositions of biochars produced from miscanthus (Miscanthus × giganteus), willow (Salix spp) and pine (Pinus sylvestris) at 500°C and at 400, 500, and 600°C in the case of the miscanthus. Although the morphologies of the cell structures were maintained in the pyrolysis, the surface area of the miscanthus biochar was greatly increased by heating at 600°C for 60 min. Nuclear magnetic resonance spectra showed the disappearance of evidence for the carbohydrate and lignin plant components as the pyrolysis temperature was raised, and the compositions of miscanthus biochars after heating for 10 and for 60 min at 600°C were very similar and composed of fused aromatic structures and with no traces of the aliphatic components in the starting materials. In greenhouse and growth chamber experiments the growth of maize (Zea mays L) seedlings was found to be inhibited by soil amendments with biochar from miscanthus formed at 400°C for 10 min, but stimulated by miscanthus char formed at 600°C for 60 min. In the course of discussion the relevance of the results obtained is related to the roles that soil amendments with biochar can have on soil fertility, carbon sequestration, on the emissions of greenhouse gases from soil, on fertilizer requirements, and on waste management. It is clear that biochar soil amendments can have definite agronomic and environmental benefits, but it will be essential to have clear guidelines for biochar production from various feedstocks and under varying pyrolysis parameters. It will be equally important to have a classification system for biochars that clearly indicate the product compositions that will meet acceptable standards. A case can be made for sets of standard biochars from different substrates that meet the required criteria.

Pub.: 12 Jun '10, Pinned: 26 Aug '17

Potential OF Biochar-Amended Soil TO Enhance Crop Productivity UNDER Deficit Irrigation†

Abstract: With the world population hitting 8 billion and the global climate becoming more erratic with pronounced droughts, floods, water shortages and storage depletions, the need for optimal soil and water conditions for high crop productivity and food security has become ever more urgent. There is a growing effort towards enhancing water storage in the root-zone soil layer (as a rainwater-harvesting strategy) to increase crop productivity. This study analysed the effects of biochar and deficit irrigation on rice productivity under greenhouse conditions. Grain yield, plant height, tiller number and biomass yield under 0% biochar (B1) were respectively 13.6, 6.4, 27.4 and 3.0% higher for moderate deficit irrigation (I2) than for flood irrigation (I1). Also in terms of tiller number, I2 performed better than I1 by 45.8 and 69.2% under B2 (4% biochar) and B4 (16% biochar), respectively. While for biochar the highest crop productivity was under B2, this changed vastly under the combined effects of irrigation and biochar. This suggested that crop productivity was as much dependent on irrigation as on biochar treatment. The variations in productivity could provide farmers with the choice of treatments or treatment combinations that are best suitable for their local agro-edaphic, hydroclimatic and socio-economic conditions. Copyright © 2017 John Wiley & Sons, Ltd.Avec une population mondiale de 8 milliards de personnes et un climat global plus irrégulier, avec des sécheresses, des inondations, des pénuries d'eau et l'appauvrissement des réserves en eau, le besoin de meilleures conditions de sol et d'eau pour une productivité et une sécurité alimentaire accrues devient de plus en plus urgent. Il y a un effort croissant pour améliorer le stockage de l'eau dans la zone racinaire (comme stratégie de récolte de l'eau de pluie) pour augmenter la productivité des cultures. Cette étude a analysé les effets du charbon agricole (biochar) et de l'irrigation déficitaire sur la productivité du riz sous serre. Le rendement en grains, la hauteur de la plante, le nombre de pieds levés et le rendement en biomasse sous 0% de biochar (B1) ont été respectivement de 13.6, 6.4, 27.4 et 3.0% plus élevés pour l'irrigation à déficit modéré (I2) que pour l'irrigation par inondation (I1). En outre, en termes de nombre de pieds levés, I2 a obtenu de meilleurs résultats que I1 de 45.8 et 69.2% sous B2 (4% de biochar) et B4 (16% de biochar), respectivement. Alors que pour le biochar la productivité la plus élevée des cultures était sous B2, les effets combinés de l'irrigation et du biochar ont sensiblement fait varier les résultats. Cela suggère que la productivité des cultures dépend autant de l'irrigation que du traitement biochar. Les variations de productivité pourraient donner aux agriculteurs le choix de choisir les traitements ou les combinaisons de traitements les mieux adaptés aux conditions agro-édaphiques, hydro-climatiques et socio-économiques locales. Copyright © 2017 John Wiley & Sons, Ltd.

Pub.: 07 Jun '17, Pinned: 26 Aug '17