Biochar and inorganic nitrogen fertilizer effects on maize (Zea mays L.) nitrogen use and yield in moist semi-deciduous forest zone of Ghana

Abstract

Maize (Zea mays L.) is a major nitrogen consuming crop, as nitrogen is considered as an important determinant of its grain yield. Though inorganic fertilizer is widely recommended, the problem of high cost and inaccessibility limit its usage by resource poor farmers. Biochar application provides a new technology for both soil fertility and crop productivity improvement. With limited research on the suitability of biochar for soil improvement practices in Ghana, our objective was to determine the synergistic effect of biochar and inorganic fertilizer on the nitrogen uptake, nitrogen use efficiency, and yield of maize. Field experiment was conducted in Ghana, KNUST, in the major and minor raining seasons. Biochar was applied at 0, 5, 10, 15, and 20 t ha^?1 and fertilizer N applied at 0, 45, and 90?kg ha^?1. The results showed significantly (p??1 supplemented with 45?kg N ha^?1 increased N uptake by 200%, and grain yield by 213% and 160% relative to the control in the minor and major rainy seasons, respectively. The greater yield of maize recorded on biochar-amended soils was attributed to the improved N uptake and nitrogen use efficiency. In conclusion, our finding suggests that the application of combined biochar and inorganic N fertilizer is not only ecologically prudent, but economically viable and a practicable alternative to current farmers’ practice of cultivating maize in Ghana.     

Effect of biochar and phosphorus fertilizer application on soil fertility: soil physical and chemical properties

This study evaluated the effect of biochar and phosphorus fertilizer application on selected soil physical and chemical properties in two contrasting soil types: Rhodic Ferralsols (clay) in Thohoyandou and Leptic Cambisols (loamy sand) in Nelspruit, South Africa. Field experiments were conducted in summer and winter. Treatments consisted of a factorial combination of four biochar levels (0, 5, 10 and 20 t ha^?1) and two phosphorus fertilizer levels (0 and 90 kg ha^?1) arranged in a randomized complete block design with three replicates. Chickpea was the test crop. Soil bulk density, aggregate stability, porosity, total C, total N, C:N ratio, K and Mg were determined. Biochar (10 t ha^?1) and phosphorus increased bulk density and decreased porosity at 0–5 and 15–20 cm soil depth on a loamy sand soil in both seasons. The interaction between biochar and phosphorus increased total C and total N on a clay soil in the summer sowing. However, in the loamy sand soil, biochar (10 t ha^?1) increased total C, C:N ratio, K and Mg in the summer sowing. The effect of biochar was more evident in the loamy sand soil than the clay soil suggesting that the influence of biochar may be soil-specific.     

Soil management for raising crop water productivity in rainfed production systems in Lao PDR

This study investigated the impacts of organic- and clay-based soil amendments, and their combinations on crop water productivity (CWP) using maize as a test crop. On-station field trials were established over two consecutive years at the Naphok and Veunkham sites in Laos. At each site, 10 treatments were applied in a randomized complete block design with three replications. The treatments were control, rice husk biochar (10 t ha^?1), bentonite clay (10 t ha^?1), compost (4 t ha^?1), clay-manure compost (10 t ha^?1), rice husk biochar compost (10 t ha^?1), bentonite clay + biochar, bentonite-clay + compost, biochar + compost, and bentonite clay + biochar + compost. All treatments were applied in 2011. Significant (p < 0.05) treatment effects in CWP and growing period evapotranspiration were determined. At Naphok, differences between the amended and control plots in CWP varied between 0.1 and 0.6 kg m^?3 in 2011 and from 0.1 to 0.4 kg m^?3 in 2012, whereas differences at Veunkham varied between 0.3 and 1.0 kg m^?3 in 2011 and from 0.05 to 0.29 kg m^?3 in 2012. At both sites, CWP in 2012 was significantly lower than 2011. Our results illustrate that organic- and clay-based soil amendments improve CWP, indicating that soil-based interventions could be suitable options for improving agricultural productivity.     

Assessment of Environment-friendly Usage of Spent Wash and its Nutritional Potential for Sugarcane Production

Excessive and inappropriate use of fertilizers is a key factor of low sugarcane yield and degradation of soil. A two-year (2013–14 and 2014–15) field study was conducted to assess the impact of combined application of organic and inorganic fertilizers on sugarcane at research farm of Shakarganj Sugar Research Institute, Jhang, Pakistan. Experiment was conducted under randomized complete block design with three replications. Treatments were used as control (no exogenous application), spent wash (160 t ha^?1), (nitrogen, phosphorus and potassium) NPK (168:112:112 kg ha^?1), spent wash (120 t ha^?1) + NPK (42:28:28 kg ha^?1), spent wash (80 t ha^?1) + NPK (84:56:56 kg ha^?1), spent wash (40 t ha^?1) + NPK (126:84:84 kg ha^?1), and spent wash (160 t ha^?1) + NPK (42:28:28 kg ha^?1). Application of spent wash @ 80 t ha^?1 + NPK @ 84:56:56 kg ha^?1 resulted maximum crop growth rate (11.35 g m^?2 d^?1), leaf area index (7.78), and net assimilation rate (2.53 g m^?2 d^?1). Maximum number of millable canes (14), weight per stripped cane (0.90 kg), stripped cane yield (117.60 t ha^?1) and unstripped cane yield (141.25 t ha^?1) were observed with spent wash @ 80 t ha^?1 + NPK @ 84:56:56 kg ha^?1, followed by sole fertilizer application @ 168:112:112 kg NPK ha^?1 and spent wash @160 t ha^?1 + NPK @ 42:28:28 kg ha^?1. Similar trend was observed regarding quality parameters. The maximum benefit–cost ratio (1.80) was achieved with integrated application of spent wash @ 80 t ha^?1 + NPK @ 84:56:56 kg ha^?1.     

Modeling of Soil-Plant-Fertilizer Relationships for Optimizing Fertilizer Doses for Different Levels of Finger Millet Yield under Semi-Arid Alfisols

Experiments were conducted to test the superiority of treatment combinations of nitrogen (N; 0, 50, 100, 150, 200 kg ha^?1), phosphorus (0, 30, 60, 90 kg ha^?1) and potassium (0, 30, 60 kg ha^?1) for finger millet during 2005–2007. Application of 200-90-60 kg ha^?1 gave maximum yield of 1666, 1426 and 1640 kg ha^?1 in 3 years, respectively. The yield regression model through soil and fertilizer nutrients gave predictability of 0.98, 0.97 and 0.98, with sustainability yield index (SYI) of 50.4, 49.4 and 52.5 in 2005, 2006 and 2007, respectively. Optimum nitrogen, phosphorus and potassium (NPK) doses for attaining yields of 800 and 1200 kg ha^?1 were derived at soil nitrogen, phosphorus and potassium of 75–400, 10–70 and 150–750 kg ha^?1. Fertilizer nitrogen, phosphorus and potassium ranged from 30–128, 3–19, 13–25 kg ha^?1 and 105–203, 4–32, 27–39 kg ha^?1 for attaining 800 and 1200 kg ha^?1 yield, respectively. The doses could be adopted for attaining sustainable yields under semiarid Alfisols.     

Effect of potassium fertilization on yield and potassium nutrition of Boro rice in a wetland ecosystem of Bangladesh

Effect of potassium (K) fertilization (0, 20, 40, 60, 80 and 100 kg K ha^?1) on yield, nitrogen (N) and K nutrition of Boro (dry season) rice and apparent soil K balance was studied. Experiment was conducted at Bangladesh Rice Research Institute (BRRI) regional station farm, Habiganj, Bangladesh during 2007–2008 to 2009–2010 in a wetland rice ecosystem under haor area. Cropping pattern was Boro–Fallow–Fallow. A popular rice variety BRRI dhan29 was tested in a randomized complete block design with three replications. Results indicated that BRRI dhan29 maintained an average grain yield of 5.19 t ha^?1 year^?1 without K fertilization. Potassium fertilization significantly increased the grain yield to 6.86 t ha^?1 year^?1. Quadratic equations best explained the progressive increase of rice yield with increasing K rates. Optimum dose of K in 3 years ranged from 78 to 93 kg ha^?1. Internal N use efficiency of rice decreased with increasing K rates. However, K use efficiency was inconsistent. Apparent K balance study revealed that application of 100 kg K ha^?1 was not able to maintain a positive K balance in soil under wetland ecosystem with Boro–Fallow–Fallow cropping system. However, K fertilization decreased the negativity of K balance in soil.     

Effects of cotton (Gossypium hirsutum L.) straw and its biochar application on NH3 volatilization and N use efficiency in a drip-irrigated cotton field

Reducing ammonia (NH₃) volatilization is a practical way to increase nitrogen (N) fertilizer use efficiency (NUE). In this field study, soil was amended once with either cotton (Gossypium hirsutum L.) straw (6 t ha^?1) or its biochar (3.7 t ha^?1) unfertilized (0 kg N ha^?1) or fertilized (450 kg N ha^?1), and then soil inorganic N concentration and distribution, NH₃ volatilization, cotton yield and NUE were measured during the next two growing seasons. In unfertilized plots, NH₃ volatilization losses in the straw-amended and biochar-amended treatments were 38–40% and 42–46%, respectively, less than that in control (i.e., unamended soil) during the two growing seasons. In the fertilized plots, NH₃ volatilization losses in the straw-amended and biochar-amended treatments were 30–39% and 43–54%, respectively, less than that in the control. Straw amendment increased inorganic N concentrations, cotton yield, cotton N uptake and NUE during the first cropping season after application, but not during the second. In contrast, biochar increased cotton N uptake and NUE during both the first and the second cropping seasons after application. Furthermore, the effects of biochar on cotton N uptake and NUE were greater in the second year than in the first year. These results indicate that cotton straw and cotton straw biochar can both reduce NH₃ volatilization and also increase cotton yield, N uptake and NUE. In addition, the positive effects of one application of cotton straw biochar were more long-lasting than those of cotton straw.     

Effect of Oil Palm Fly Ash on Soil Properties and Yield of Sweet Corn in the Tropical Zone of Thailand

Disposal of oil palm fly ash (OPFA) into the environment causes environmental pollution. A field experiment was conducted to evaluate the effects of OPFA and mineral fertilizer on soil properties and yield of sweet corn. A total of six treatments were applied that included 2, 4, and 6 t ha^–1 OPFA, 200 kg ha^–1 nitrogen, phosphorus, and potassium (NPK), 100 kg ha^–1 NPK + 2 t ha^–1 OPFA as well as the control. A significant increase in soil pH and available P was observed with the sole OPFA treatments at 2, 4, and 6 t ha^–1, while a significant increase in exchangeable cations [K, magnesium (Mg)] was detected only at the 6-t ha^–1 OPFA treatment. The highest grain yield of 4220 kg ha^–1 was obtained at the 100-kg ha^–1 NPK + 2 t ha^–1 OPFA-treated plots, which was statistically similar with the grain yield of 3800 kg ha^–1 received at the 200-kg ha^–1 NPK-treated plots. The practical implication of this study is that OPFA can be used as a liming material to increase soil pH and it has a synergetic effect in combination with inorganic fertilizer.     

Growth,yield and water use efficiency of chickpea (Cicer arietinum): response to biochar and phosphorus fertilizer application

Field experiments were conducted during summer (2013/2014) and winter (2014) in two different soil types to evaluate the effect of biochar and P fertilizer application on growth, yield, and water use efficiency of chickpea. Soil types include Rhodic Ferralsols (clay) in Thohoyandou and Leptic Cambisols (loamy sand) in Nelspruit, South Africa. Treatments consisted of a factorial combination of four biochar levels (0, 5, 10 and 20 t ha^?1) and two phosphorus fertilizer levels (0 and 90 kg ha^?1) arranged in a randomized complete block design and replicated three times. Biochar application at 5 t ha^?1 significantly increased biomass, grain yield and water use efficiency of biomass production (WUE_b) in the clay soil compared to 10 and 20 t ha^?1. However, the increase was attributed to the addition of P fertilizer. Biochar application had no effect on yield components in the loamy sand soil, but P fertilizer addition increased number of seeds/pod in the loamy sand soil and number of pods/plant in the clay soil. Biochar and P fertilizer application on growth and yield of chickpea varied in soil types and seasons, as the effect was more prominent in the clay soil than the loamy sand soil during the summer sowing.     

Effects of bamboo biochar application on global warming in paddy fields in Ehime prefecture,Southern Japan

Biochar application can reduce global warming via carbon (C) sequestration in soils. However, there are few studies investigating its effects on greenhouse gases in rice (Oryza sativa L.) paddy fields throughout the year. In this study, a year-round field experiment was performed in rice paddy fields to investigate the effects of biochar application on methane (CH₄) and nitrous oxide (N₂O) emissions and C budget. The study was conducted on three rice paddy fields in Ehime prefecture, Japan, for 2 years. Control (Co) and biochar (B) treatments, in which 2-cm size bamboo biochar (2 Mg ha^?1) was applied, were set up in the first year. CH₄ and N₂O emissions and heterotrophic respiration (Rh) were measured using a closed-chamber method. In the fallow season, the mean N₂O emission during the experimental period was significantly lower in B (67 g N ha^?1) than Co (147 g N ha^?1). However, the mean CH₄ emission was slightly higher in B (2.3 kg C ha^?1) than Co (1.2 kg C ha^?1) in fallow season. The water-filled pore space increased more during the fallow season in B than Co. In B, soil was reduced more than in Co due to increasing soil moisture, which decreased N₂O and increased CH₄ emissions in the fallow season. In the rice-growing season, the mean N₂O emission tended to be lower in B (?104 g N ha^?1) than Co (?13 g N ha^?1), while mean CH₄ emission was similar between B (183 kg C ha^?1) and Co (173 kg C ha^?1). Due to the C release from applied biochar and soil organic C in the first year, Rh in B was higher than that in Co. The net greenhouse gas emission for 2 years considering biochar C, plant residue C, CH₄ and N₂O emissions, and Rh was lower in B (5.53 Mg CO₂eq ha^?1) than Co (11.1 Mg CO₂eq ha^?1). Biochar application worked for C accumulation, increasing plant residue C input, and mitigating N₂O emission by improving soil environmental conditions. This suggests that bamboo biochar application in paddy fields could aid in mitigating global warming.     

Compost and Nitrogen Management Influence Productivity of Spring Maize (Zea mays L.) under Deep and Conventional Tillage Systems in Semi-arid Regions

On-farm research was conducted to investigate the effects of nitrogen (N) and compost (C) on yield and yield components of spring maize (Zea mays L.) under conventional and deep tillage system (T) at the research farm of the University of Agriculture, Peshawar, Pakistan, during spring 2013. The experiment was laid out in a randomized complete block design with split-plot arrangement, using three replications. Three compost levels (0, 1, and 2 t ha^?1) and two tillage systems (conventional and deep tillage) were allotted to the main plot, whereas N levels (60, 90, 120, and 150 kg N ha^?1) were allotted to subplots in the form of urea. Nitrogen and compost levels had significantly affected all the parameters. Plots treated with 150 kg N ha^?1 increased ear length (31 cm), grains ear^?1 (413), thousand-grain weight (240.2 g), grain yield (3097 kg ha^?1), straw yield (9294 kg ha^?1), harvest index (24.7 percent), and shelling percentage (81.7 percent). Compost applied at 2 t ha^?1 increased ear length (32 cm), grains ear^?1 (430), thousand-grain weight (242.3 g), grain yield (2974 kg ha^?1), straw yield (8984 kg ha^?1), harvest index (24.6 percent), and shelling percentage (83.2 percent). Tillage system had significant effect on all parameters except ear length and harvest index. Deep tillage system produced more grains ear^?1 (365), thousand-grain weight (233.3 g), grain yield (2630 kg ha^?1), straw yield (8549 kg ha^?1), and shelling percentage (79.6 percent). It was concluded from the results that application of 120 kg N ha^?1 + 2 C t ha^?1 under a deep tillage system could improve spring maize yield and yield-contributing traits under semi-arid conditions.     

Evaluation of yield and some physiological changes in corn and sorghum under irrigation regimes and application of barley residue,zeolite and superabsorbent polymer

In order to investigate the changes in chlorophyll fluorescence, chlorophyll, relative water content (RWC) and forage yield of corn and sorghum under various irrigation regimes and combination treatments of barley residue, zeolite and superabsorbent polymer, an experiment was conducted over 2 years in Kerman, Iran. A randomized complete block design arranged in a factorial split was used with three replications. Two irrigation regimes of normal and drought stress based on 70 and 140 mm cumulative pan evaporation, respectively, and two plant species (corn and sorghum) as factorial combinations were compared in the main plots. Five treatments, (1) 10 t ha^?1 zeolite + 4.5 t ha^?1 residue, (2) 60 kg ha^?1 superabsorbent + 4.5 t ha^?1 residue, (3) 5 t ha^?1 zeolite + 30 kg ha^?1 superabsorbent + 4.5 t ha^?1 residue, (4) 4.5 t ha^?1 residue and (5) – control, were compared in subplots. In both plants, forage yield, potential quantum yield (Fv/Fm), chlorophyll a, total chlorophyll and carotenoid contents decreased significantly under drought stress. Chlorophyll a content, SPAD index and Fv/Fm were higher in corn than in sorghum, but RWC was higher in sorghum. Corn produced higher forage yield (62.8 t ha^?1) than sorghum (49.3 t ha^?1). The application of 10 t ha^?1 zeolite with 4.5 t ha^?1 residue increased most traits more than any of the other treatments, but the superabsorbent had no significant effect on the studied traits.     

Biochar and fertiliser applications influence phosphorus fractionation and wheat yield

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.     

Efficiency of Potassium Fertilization and Salicylic Acid on Yield and Nutrient Accumulation of Sugar Beet Grown on Saline Soil

Rising soil salinity has been a major problem in the soils of Egypt in recent decades. Potassium fertilization and salicylic acid (SA) play an important role in promoting plants to tolerate salt stress and increased the yield of sugar beet crop. A field experiment on sugar beet (Beta vulgaris L.) grown on saline soil was carried out during 2014 growing season in Port Said Governorate, Egypt, to study the effect of potassium fertilization of the soil at applications of 0, 100, 150, and 200 kg potassium (K) ha^?1 and foliar spray of SA by solution of 1000 mg L^?1, twice (1200 L ha^?1 each time) on yield and nutrient uptake. Application of 200 kg K ha^?1 in combination with salicylic foliar spray gave the highest root length, root diameter, shoot and root yield, sucrose, juice purity percentage, gross sugar yield, and white possible extractable sugar, nitrogen (N), phosphorus (P), and potassium (K) content, and uptake of sugar beet. The highest increase in sucrose (20%) as well as white possible extractable sugar (184%) was obtained by 200 kg K ha^?1 in combination with salicylic foliar spray compared with untreated soil with potassium fertilization and without salicylic foliar spray.     

Potassium fertilization and soil diagnostic criteria for forage corn (Zea mays L.) production contributing to lower potassium input in regional fertilizer recommendation

Abstract

Effective soil diagnostic criteria for exchangeable potassium (Ex-K) combined with inorganic potassium (K) application rates were developed to lower K input in forage corn (Zea mays L.) production using experimental fields with different application rates and histories of cattle manure compost. Two corn varieties, ‘Cecilia’ as a low K uptake variety and ‘Yumechikara’ as a high K uptake variety, were selected from among 20 varieties and tested to make diagnostic criteria for K fertilization applicable to varieties with different K uptakes. The K uptakes increased from 96 to 303 kg K ha^?1 for ‘Cecilia’ and from 123 to 411 kg K ha^?1 for ‘Yumechikara’ with increasing Ex-K content on a dry soil basis from 0.11 to 0.92 g kg^?1 with no inorganic K fertilizer application. The K uptake by corn for achieving the target dry matter yield of 18 Mg ha^?1 was estimated to be approximately 200 kg K ha^?1 in common between the two varieties. Yields of both varieties achieved the target yield at an Ex-K content of approximately 0.30 g kg^?1 with no K fertilization, although ‘Yumechikara’ reached the target yield at a lower Ex-K content. At the low Ex-K content of 0.1 g kg^?1, inorganic K fertilizer application at 83 kg K ha^?1 was needed to gain the target yield, and apparent K recovery rate for K fertilizer was calculated to be 70% for both varieties. The K uptakes for gaining the target yield by the K fertilization were lower than that by soil K supply. Based on these results, diagnostic criteria of Ex-K and inorganic K application rates were set up as follows: at an Ex-K content of < 0.15 g kg^?1, inorganic K fertilizer is applied at 83 kg K ha^?1 (100 kg ha^?1 as potassium oxide (K₂O) equivalent); at an Ex-K content of 0.15–0.30 g kg^?1, the application rate is reduced to 33 kg K ha^?1 (40 kg K₂O ha^?1); at an Ex-K content of ≥ 0.30 g kg^?1, inorganic K fertilizer is not applied because of sufficient K in the soil. Additionally, we propose that cattle manure compost be used to supplement soil K fertility.     

Biochar combined with nitrogen fertilizer affects soil properties and wheat yield in medium-low-yield farmland

Biochar combined with fertilizer as a soil amendment benefits to improving soil fertility, especially soil organic carbon and crop yield. However, the effect of biochar on the improvement of soil properties and crop yield was varied from soil properties and limited for medium–low-yield farmland in the North China. During the completely randomized field experiment, SIX treatments (biochar applied as 0, 15 and 30 t·ha^-1, under 240 and 300 kg N ha^-1 nitrogen fertilizer) were applied in wheat season and examined to reveal changes in the SOC and other properties of 0- to 10-cm and 10- to 20-cm soil layers. The results showed that two years after the application of biochar, a significant increase in the SOC was observed, ranging from 19.52% to 97.50% (p < 0.05) in the 0- to 20-cm soil layer. Wheat yield and SOC content increased with increasing amount of biochar applied under the same amount of nitrogen fertilizer. The content of soil available potassium increased significantly under 30 t·ha^-1 biochar application (p < 0.05). Both biochar and nitrogen fertilizer application could increase wheat yield, and the effect of biochar application for increasing wheat yield was better than that of nitrogen fertilizer. Wheat yield and SOC content increased with increasing nitrogen fertilizer at the same amount of biochar application. The principal component analysis results showed that biochar input, SOC, available potassium and total nitrogen were the key factors affecting wheat yield. Biochar application is a fast and effective measure to improve SOC and wheat yield in medium- and low-yield farmlands.     

Wheat straw and its biochar had contrasting effects on soil C and N cycling two growing seasons after addition to a Black Chernozemic soil planted to barley

Application of crop residues and its biochar produced through slow pyrolysis can potentially increase carbon (C) sequestration in agricultural production systems. The impact of crop residue and its biochar addition on greenhouse gas emission rates and the associated changes of soil gross N transformation rates in agricultural soils are poorly understood. We evaluated the effect of wheat straw and its biochar applied to a Black Chernozemic soil planted to barley, two growing seasons or 15 months (at the full-bloom stage of barley in the second growing season) after their field application, on CO₂ and N₂O emission rates, soil inorganic N and soil gross N transformation rates in a laboratory incubation experiment. Gross N transformation rates were studied using the ¹⁵N isotope pool dilution method. The field experiment included four treatments: control, addition of wheat straw (30 t ha^?1), addition of biochar pyrolyzed from wheat straw (20 t ha^?1), and addition of wheat straw plus its biochar (30 t ha^?1 wheat straw + 20 t ha^?1 biochar). Fifteen months after their application, wheat straw and its biochar addition increased soil total organic C concentrations (p?=?0.039 and <0.001, respectively) but did not affect soil dissolved organic C, total N and NH₄ ⁺-N concentrations, and soil pH. Biochar addition increased soil NO₃ ^?-N concentrations (p?=?0.004). Soil CO₂ and N₂O emission rates were increased by 40 (p?p?=?0.03), respectively, after wheat straw addition, but were not affected by biochar application. Straw and its biochar addition did not affect gross and net N mineralization rates or net nitrification rates. However, biochar addition doubled gross nitrification rates relative to the control (p?2 and N₂O emissions and enhance soil C sequestration. However, the implications of the increased soil gross nitrification rate and NO₃ ^?-N in the biochar addition treatment for long-term NO₃ ^?-N dynamics and N₂O emissions need to be further studied.     

Biochar use in a legume–rice rotation system: effects on soil fertility and crop performance

The aim of this study was to determine whether by applying biochar, it is possible to augment the beneficial effects of legume–crop rotation systems on soil fertility and crop performance. Repeated experiments were established in 2012 and 2013 in South-western Benin using a split-split plot design. Two legumes, Mucuna pruriens (mucuna) and Vigna unguiculata (cowpea), were planted for 42 days on biochar-amended and unamended plots and subsequently cut and applied as mulch 5 days before planting rice. Rice plants were either fertilized or not using a fertilizer rate of 60, 30, and 30 kg ha^?1 of N, P₂O₅, and K₂O, respectively. The results showed that the application of legume green manures and fertilizer, either singly or in combination, improved soil nutrient availability, CEC, shoot yield, and grain yield of rice on both biochar-amended and unamended plots. However, the effect was significantly (p < 0.05) greater on biochar-amended plots. The mean grain yield for all cropping seasons was 1.8 t ha^?1 for biochar-amended plots and 1.3 t ha^?1 for unamended plots. The greater grain yield of rice on biochar-amended plots was associated with improved soil fertility and increased N uptake.     

Biochar amendment changes temperature sensitivity of soil respiration and composition of microbial communities 3 years after incorporation in an organic carbon-poor dry cropland soil

Topsoil samples were collected from plots in a dry cropland in the North China Plain 3 years after a single incorporation of biochar at 20 and 40 t ha^?1 and analyzed for abundances and composition of microbial community and for respiration under controlled laboratory conditions at 15, 20, and 25 °C. The addition of biochar generally reduced soil respirations at the three temperatures and the temperature sensitivity (Q₁₀) at 15–20 °C. Biochar amendment significantly increased bacterial 16S rRNA gene abundances and fungal ITS gene diversity and induced clear changes in their community compositions due to improvements in soil chemical properties such as soil organic C (SOC) and available N contents and pH. Illumina Miseq sequencing showed that the relative abundances of Actinobacteria, Gammaproteobacteria, Firmicutes, and Alternaria within Ascomycota, capable of decomposing SOC, were significantly decreased under biochar at 40 t ha^?1. The Q₁₀ values at 15–20 °C were significantly correlated with fungal diversity and dehydrogenase activity. Our results suggest that after 3 years a single biochar amendment could induce a shift in microbial community composition and functioning towards a slower organic C turnover and stability to warming, which may potentially reduce soil C loss in dryland under climate warming in the future.     

Effect of Combined Use of Organic and Inorganic Sources of Nutrients on Sunflower Yield,Soil Fertility,and Overall Soil Quality in Rainfed Alfisol

Abstract

To study the response of inorganic and organic nitrogen (N) sources both alone and in conjunction and their influence on soil quality, a field experiment was conducted during kharif and rabi seasons using sunflower (MSFH‐8) as test crop. The experimental site soil was Typic Haplustalf situated at Hayatnagar Research Farm of Central Research Institute of Dryland Agriculture, Hyderabad, India, at 17° 18′ N latitude, 78° 36′ E longitude. The experiment design was a simple randomized block design with 11 treatments replicated four times. Among all the treatments, vermicompost (VC)+Fert at 25+25 kg N ha^?1 recorded the highest grain yields of 1878 and 2160 kg ha^?1 during both kharif and rabi seasons, respectively, which were 43.9 and 85.1% higher than their respective control plots. Apparent N recovery varied from as little as 38.30% (FYM at 50 kg N ha^?1) to 62.16 (25 kg N ha^?1) during kharif and 49.65 (75 kg ha^?1) to 83.28% (VC+Fert at 25+25 kg N ha^?1) during rabi season. Conjunctive nutrient treatments proved quite superior to other set of treatments in improving the uptake of N, phosphorus (P), potassium (K), sulfur (S), and micronutrients in sunflower and their buildup in the soil. Highest relative soil quality indexes (RSQI) were observed under VC+Fert at 25+25 kg N ha^?1 (1.00) followed by VC+Gly at 25+25 kg N ha^?1 (0.87). Considering the yield and relative soil quality indices (RSQI), conjunctive applications of VC with either inorganic fertilizer, FYM, or Gly at 25+25 kg N ha^?1 could be a successful and sustainable soil nutrient management practice in semi‐arid tropical Alfisols. Besides this, the fertilizer N demand could be reduced up to 50%.