Fertilizer Amendments Research Articles

Linking sorghum nutrition and production with arbuscular mycorrhizal fungi and alternative soil amendments

Mounting fertilizer costs are disproportionally affecting farmers in developing countries. Alternative soil fertility amendments [worm compost, pyrolyzed carbon (biochar)] and arbuscular mycorrhizal fungi have the potential to reduce these costs while promoting soil health. Our greenhouse study investigated the role of mycorrhizal associations and alternative fertility amendments on the productivity and plant nutrition of grain sorghum. We assessed sorghum (Sorghum bicolor cv. Macia) grown with ten different treatments (combinations of biochar, worm compost, and commercial N and P fertilizers) plus a non-amended control. An amendment blend containing worm compost, biochar, and 50% of the typically recommended commercial fertilizer rate produced similar plant biomass and protein, similar total tissue mineral contents (Ca, Fe, K, Mg, P, and Zn), and supported ≈ 60% more mycorrhizal fungi in the host plant's roots, compared to sorghum grown with the recommended rate of commercial fertilizer (N and P). Our results indicate the potential of biochar and worm compost to enhance the benefits of mycorrhizal fungi for grain sorghum production and plant nutrition while reducing commercial fertilizer applications.

The role of indigenous knowledge and practice on water and soil conservation management in Albuko Woreda, Ethiopia

Abstract Taye A, Megento TL. 2017. The role of indigenous knowledge and practice on water and soil conservation management in Albuko Woreda, Ethiopia. Bonorowo Wetlands 7: 95-107. The objectives of this study were to assess various aspects of indigenous knowledge and practice in water and soil conservation measures introduced in Albuko Woreda/district, South Wollo, Ethiopia, and investigate how farmers have adopted indigenous soil and water conservation measures. This study also aimed to examine farmers' views on land degradation and assess their adoption behavior of soil and water conservation knowledge. The data for the study originated mainly from farmers in the study area. Structured questionnaire survey and focus group discussion methods were applied to collect the necessary information from farm households. A total of 140 heads of families were questioned. The received data was analyzed using descriptive statistics and quantitative and qualitative data analysis. Even though some soil and water conservation methods were introduced to combat land degradation in Ethiopia, adopting these practices remains below expectations. Most farmers preferred soil (stone) bund, water diversion ditch and contour ploughing for soil and water conservation, crop rotation, and mixed cropping for soil fertility amendment measures instead of traditional cutoff drain and fallowing. Farmers faced several constraints in adopting soil and water conservation measures. The main problems related to conservation structures include the source of pests, inconveniency during ox ploughing, reduction of farmland, labor intensiveness, difficulty in implementation, and costliness. In contrast, farmers were knowledgeable about various indigenous soil and water conservation measures but implemented only some of them. They understand the effects of erosion on crop productivity. Finally, farmers need to be trained on the impact of soil erosion and available conservation measures. Information on the ineffectiveness of some traditional conservation measures has to be disseminated among farmers.

Manure amendment increases the content of nanomineral allophane in an acid arable soil

Natural nanoparticles are of central importance in the environment, e.g. sorption of soil organic carbon (SOC) and contaminants. A large number of study have focused on the metal binding, transport and ecotoxicity of nanoparticles. Fertilizer amendments are routinely applied to arable soils and induce changes in soil chemical, physical and biological properties. However, the effects of fertilizer amendments on natural nanoparticles are still unknown. In this study, soil nanoparticles were separated from acid red soil (Ferralic Cambisol) including long-term (26 years) treatments of unfertilized control (CK), chemical nitrogen, phosphorus and potassium fertilizers (NPK) and raw pig manure (M). The results from high-resolution transmission electron microscopy (HRTEM) and Fourier-transformed infrared (FTIR) spectroscopy indicated that nanoparticles in red soil were heterogeneous organo-mineral associations with irregular shapes, regardless of fertilization history. In addition, kaolinite and allophane occurred in the soil nanoparticles. Intriguingly, we found the content of allophane under M treatment (0.64 g kg−1) was much higher than under CK and NPK treatments. However, the CK (0.27 g kg−1) and NPK (0.21 g kg−1) had similar allophane concentrations. Our study may indicate long-term organic manure amendment initializes positive feedback loop for further SOC sequestration. However, the mechanisms for the enhancement of nanomineral allophane by manure amendment deserve further investigation.

Soil protist communities form a dynamic hub in the soil microbiome.

Soil microbes are essential for soil fertility. However, most studies focus on bacterial and/or fungal communities, while the top-down drivers of this microbiome composition, protists, remain poorly understood. Here, we investigated how soil amendments affect protist communities and inferred potential interactions with bacteria and fungi. Specific fertilization treatments impacted both the structure and function of protist communities. Organic fertilizer amendment strongly reduced the relative abundance of plant pathogenic protists and increased bacterivorous and omnivorous protists. The addition of individual biocontrol bacteria and fungi further altered the soil protist community composition, and eventually function. Network analysis integrating protist, bacterial and fungal community data, placed protists as a central hub in the soil microbiome, linking diverse bacterial and fungal populations. Given their dynamic response to soil management practices and key position in linking soil microbial networks, protists may provide the leverage between soil management and the enhancement of bacterial and fungal microbiota at the service of improved soil health.

Effect of calcium silicate on nutrient use of lowland rice and greenhouse gas emission from a paddy soil under alternating wetting and drying

In intensively irrigated rice cultivation, plant-available silicon (Si) is a crucial nutrient for improving rice productivity. As a source of Si, calcium silicate (CaSiO3) was amended to evaluate the effect of silicate fertilizer on rice production, nitrogen (N) use efficiency, and greenhouse gas (GHG) emission under alternating wetting and drying in a pot experiment using a tropical soil from a paddy field of the International Rice Research Institute (IRRI) in the Philippines. Four levels of CaSiO3 amendment, 0, 112.7, 224.5, and 445.8 kg ha–1, with the recommended N rate were tested. The results showed that although CaSiO3 amendment of 112.7 kg ha–1 resulted in higher rice straw, improved N use efficiency, and reduced N2O emission, there was no difference in grain yield among the four levels of CaSiO3 amendment owing to relatively lower harvest index. Moreover, CaSiO3 amendment showed a reverse trend between CH4 and N2O emissions as it reduced N2O emission while led to significantly increased CH4 emission and global warming potential. Thus, CaSiO3 amendment was a possible alternative to improve N use efficiency and increase rice straw biomass, but it needs to be reviewed in line with grain yield production and GHG emission. It is also imperative to test an optimal method of silicate fertilizer amendment in future research in order to compromise a negative impact in tropical soils.

Bio-fertilizer application induces soil suppressiveness against Fusarium wilt disease by reshaping the soil microbiome

Fusarium wilt disease is a growing problem in agriculture systems. Application of bio-fertilizers containing beneficial microbes represents a promising disease control strategy. However, the mechanisms underlying disease suppression remain elusive. Here, in order to assess the importance of direct antagonism and modified soil microbiota on suppression of Fusarium wilt disease, we conducted a pot experiment with chemical, organic and biologically enhanced fertilizers, we tracked the impact of those fertilizer amendments on disease incidence, and measured the pathogen density and changes in soil microbiota. Alterations in bacterial abundance and community structure after bio-fertilizers application were determined to be key factors in constraining the pathogen, Fusarium oxysporum. In particular, bio-fertilizer application increased the abundance of indigenous microbial groups with reported antifungal activity, such as Lysobacter spp., which could play a keystone role in controlling this pathogen. The microbes introduced in the bio-fertilizer treatments (e.g. Bacillus and Trichoderma spp.) induced suppressiveness via alteration of the soil microbiome rather than direct pathogen inhibition. These results contrast with the commonly held paradigm of disease suppression using beneficial microbes and open up new perspectives for the promotion of soil health. In addition to seeking antagonistic microbes based on their direct inhibitory activity, disease suppression may also be achieved by introducing keystone species that reshape soil microbiome structure and function.

Assessing the influence of farm fertility amendments, field management, and sorghum genotypes on soil microbial communities and grain quality

It is imperative for sorghum breeders to focus on enhancing plant-microbial partnerships to help deliver efficient genotypes for sustainable agricultural systems. Alternative farm fertility amendments and field management practices may also improve sorghum yields and grain quality, especially in combination with appropriately bred genotypes. Therefore, we assessed four genotypes of grain sorghum (two commercial hybrids and two landrace open-pollinated cultivars) for their influence on soil microbial communities, particularly arbuscular mycorrhizal fungi, at two field sites. All genotypes were grown as sole crops, while one commercial hybrid and one open-pollinated cultivar were also intercropped with cowpea to compare the two farm management practices. We established three treatments: non-amended control, commercial fertilizers (N and P), and worm compost (alternative fertility amendment). Grain production and nutritional quality were assessed to link belowground influences from genotypes and management on aboveground outcomes. Soil microbial communities were influenced by genotype, and higher fungal to bacterial biomass ratio was observed following worm compost amendment. Grain production was not significantly different between genotypes or treatments; however, percentage mycorrhizal root colonization was significantly greater for plants grown in soil amended with worm compost, as compared to commercial fertilizers. Genotype also had a significant effect on grain nutritional quality, while intercropping and/or amendment with worm compost generally resulted in similar or improved grain quality as compared to sole cropping and/or amendment with commercial fertilizers. Selective breeding of sorghum for agricultural systems designed around these alternative practices may further benefit grain nutrition and soil microbial communities.

Effects of topography and vegetation on distribution of rare earth elements in calcareous soils

This study investigated the impact of topography and vegetation on distribution of rare earth elements (REEs) in calcareous soils using methods of single extraction and mass balance calculation. The purposes of the study were to set a basis for further research on the biogeochemical REE cycle and to provide references for soil–water conservation and REE-containing fertilizer amendments. The results show a generally flat Post-Archean Average Australian Shale—normalized REE pattern for the studied calcareous soils. REE enrichment varied widely. The proportion of acid-soluble phases of heavy REEs was higher than that of light REEs. From top to bottom of the studied hills, dominant REE sources transitioned from limestone in-situ weathering to input from REE-containing phases (e.g., clay minerals, amorphous iron, REE-containing fluids). Our results indicate that the REE content of calcareous soils is mainly controlled by slope aspect, while the enrichment degree of REEs is related to geomorphological position and vegetation type. Furthermore, the proportion of acid-soluble phases of REEs is mainly controlled by geomorphological position.

Effects of vermicompost amendment as a basal fertilizer on soil properties and cucumber yield and quality under continuous cropping conditions in a greenhouse

PurposeWe examined the effects of vermicompost application as a basal fertilizer on the properties of a sandy loam soil used for growing cucumbers under continuous cropping conditions when compared to inorganic or organic fertilizers.Materials and methodsA commercial cucumber (Cucumis sativus L.) variety was grown on sandy loam soil under four soil amendment conditions: inorganic compound fertilizer (750 kg/ha,), replacement of 150 kg/ha of inorganic compound fertilizer with 3000 kg/ha of organic fertilizer or vermicompost, and untreated control. Experiments were conducted in a greenhouse for 4 years, and continuous planting resulted in seven cucumber crops. The yield and quality of cucumber fruits, basic physical and chemical properties of soil, soil nutrient characteristics, and the soil fungal community structure were measured and evaluated.Results and discussionContinuous cucumber cropping decreased soil pH and increased electrical conductivity. However, application of vermicompost significantly improved several soil characteristics and induced a significant change in the rhizosphere soil fungal community compared to the other treatments. Notably, the vermicompost amendments resulted in an increase in the relative abundance of Ascomycota, Chytridiomycota, Sordariomycetes, Eurotiomycetes, and Saccharomycetes, and a decrease in Glomeromycota, Zygomycota, Dothideomycetes, Agaricomycetes, and Incertae sedis. Compared to the organic fertilizer treatment, vermicompost amendment increased the relative abundance of beneficial fungi and decreased those of pathogenic fungi. Cucumber fruit yield decreased yearly under continuous cropping conditions, but both inorganic and organic fertilizer amendments increased yields. Vermicompost amendment maintained higher fruit yield and quality under continuous cropping conditions.ConclusionsContinuous cropping decreased cucumber yield in a greenhouse, but basic fertilizer amendment reduced this decline. Moreover, basal fertilizer amendment decreased beneficial and pathogenic fungi, and the use of vermicompost amendment in the basic fertilizer had a positive effect on the health of the soil fungal community.

Wheat straw-derived biochar amendment stimulated N2O emissions from rice paddy soils by regulating the amoA genes of ammonia-oxidizing bacteria

Biochar amendment of upland soil has been generally accepted to mitigate nitrous oxide (N2O) emissions. However, this is not always the case in rice paddy soil, and the underlying mechanisms are not well understood. To evaluate how biochar amendment affects N2O production and emissions in paddy soil, an incubation experiment was designed including six treatments: wheat straw-derived biochar (slow pyrolyzed at 400 °C) amendment at rates of 0% (Control), 1% and 4% soil mass (w/w), inorganic nitrogen (N) fertilizer amendment (with urea), and N fertilizer plus 1% biochar and 4% biochar. The application of 4% biochar significantly increased N2O emissions from N-unfertilized and fertilized soils during the 45-day incubation, by 291% and 256%, respectively, while 1% biochar amendment significantly increased soil N2O emissions when accompanied by N fertilizer addition. On day 14, when the N2O emission peaks occurred, N2O flux was significantly correlated with soil pH in all treatments. Biochar addition also enhanced the abundance of ammonia-oxidizing bacteria (AOB) amoA genes, which was significantly related to soil pH. Among all detected N2O-forming and reducing microbial genes, the abundance of AOB amoA genes was most closely related to N2O flux. On biochar addition, the AOB community structure shifted from Nitrosospira-dominated toward Nitrosomonas, and the diversity of AOB was significantly increased. Compared with the control, biochar amendment decreased, albeit not significantly, the abundance of the nitrous oxide reductase encoding gene nosZ, but did not alter the abundance of nitrite reductase encoding genes nirK and nirS. Our study suggests that wheat straw-derived biochar amendment of paddy soils increased soil pH, which in turn increased the abundance and diversity of AOB and N2O emissions.

Effects of industrial and agricultural waste amendment on soil greenhouse gas production in a paddy field in Southeastern China

Controlling the production and subsequent emissions of greenhouse gases (GHGs) from paddy fields is crucial to minimize the climatic impacts arising from crop production. The application of chemical or biological amendments is one possible way to limit the production of GHGs in paddy soils. Yet, few existing studies have examined the impacts of applying fertilizers originated from industrial and agricultural wastes on soil GHG production and its governing factors in subtropical paddy fields. In this study, we examined the effects of various agricultural and industrial amendments, including biochar, steel slag, shell slag, gypsum slag, and slag-derived silicate and calcium fertilizers, on the production potential of GHGs in an early paddy field in southeast China. The mean CO2 production rates from soils amended with steel slag as well as silicate and calcium fertilizers were significantly higher than those of the controls by 13.4% and 18.6%, respectively (P < 0.05). Mean soil CH4 production rates from the plots amended with steel slag, biochar, shell slag, and gypsum slag were significantly lower than those of the controls by 42.5%, 36.1%, 60.8%, and 61.8%, respectively (P < 0.05). Meanwhile, we found no significant difference in mean soil N2O production rates between the control and any of the treatments (P > 0.05). Overall, the soil production rate of CO2 was positively correlated with that of CH4 (P < 0.05), but negatively correlated with that of N2O (P < 0.05). When compared to the controls, the ratio of soil CO2:CH4 production increased significantly in the plots receiving biochar, and silicate and calcium fertilizer amendments (P < 0.05), while that of CO2:N2O production increased significantly only in the biochar-amended plots. Soil CH4:N2O production ratio decreased significantly in the plots amended with steel slag and gypsum slag, as compared to the controls (P < 0.05). Our results suggest that the application of biochar, shell slag and gypsum slag would help reduce greenhouse gas production and mitigate climate change impacts of rice cultivation, largely attributable to the reduction in methanogenesis.

Effects of feeding pregnant beef cows selenium-enriched alfalfa hay on selenium status and antibody titers in their newborn calves.

ABSTRACTIn newborn dairy calves, it has been demonstrated that supranutritional maternal and colostral Se supplementation using Se yeast or sodium selenite, respectively, improves passive transfer of IgG. In beef cattle, agronomic biofortification with Se is a more practical alternative for Se supplementation, whereby the Se concentration of hay is increased through the use of Se-containing fertilizer amendments. It has been previously demonstrated that agronomic Se biofortification is an effective strategy to improve immunity and performance in Se-replete weaned beef calves. The objective of this experiment was to determine the effects of feeding beef cows Se-enriched alfalfa (Medicago sativa) hay during the last 8 to 12 wk of gestation on passive transfer of antibodies to calves. At 10 wk ± 16 d before calving, 45 cows were assigned to 1 of 3 treatment groups with 3 pens (5 cows/pen) per treatment: Control cows were fed non-Se-fortified alfalfa hay plus a mineral supplement containing 120 mg/kg Se from sodium selenite, Med-Se cows were fed alfalfa hay fertilized with 45.0 g Se/ha as sodium selenate, and High-Se cows were fed alfalfa hay fertilized with 89.9 g Se/ha as sodium selenate; both the Med-Se and the High-Se groups received mineral supplement without added Se. Colostrum and whole blood (WB) were collected from cows at calving, and WB was collected from calves within 2 h of calving and at 12, 24, 36, and 48 h of age. Concentrations of IgG1 and J-5 Escherichia coli antibody in cow colostrum and calf serum were quantified using ELISA procedures. Selenium concentrations linearly increased in WB (P < 0.001) and colostrum (P < 0.001) of cows and in WB of newborn calves (P < 0.001) with increasing Se concentration in alfalfa hay. Colostrum concentrations of IgG1 (P = 0.03) were increased in cows fed Se-biofortified alfalfa hay, but J-5 E. coli antibody (P = 0.43) concentrations were not. Calf serum IgG1 (P = 0.43) and J-5 E. coli antibody (P = 0.44) concentrations during the first 48 h of age were not affected by prior Se treatment of cows. These data suggest that feeding Se-biofortified alfalfa hay promotes the accumulation of Se and antibodies in colostrum but does not affect short-term serum antibody concentrations in calves.

Evaluation of micronutrient status of sandy clay loam as influenced by sulphur fertilization on blackgram

Secondary nutrient deficiency especially sulphur (S) in blackgram has imparted poor grain setting percentage and yield as well. Interest on S availability in soils has increased due to acute shortage production of quality blackgram. Therefore, an attempt was made to assess the three SO4-2- S sources (Gypsum, Ammonium sulphate and Potassium sulphate) and two S levels (10 and 20 kg S ha-1) under irrigated condition. This experimental trial was replicated three times along with randomized block design at farmer field of Thenamallur village, T. Kallikudi block, Madurai district. S treatments were also evaluated by two methods of fertilizer amendment such as, soil application (as basal dose) and foliar spray (0.5 % K2SO4) on 30th and 45th days after sowing and its combinations. Soil analysis is good method to assess the S nutritional status of soil under tropical areas. The results revealed that the S and micronutrient content was low in single soil application or foliar spray and irrespective of source and level. Foliar spray treatment plants recovered limited S concentration. We could found that the better higher S concentration among the combination treatments. Soil application of K2SO4 @ 20 kg ha-1 + foliar spray was increased the soil available S and DTPA - extractable Micronutrient (Zn, Fe, Mn and Cu) status. Our study explains that the treatment combinations had synergistic effect and it may be concluded that the combinations (soil + foliar spray) are increased soil available S and micronutrient status. Further, future studies are required to confirm the results of S fertilizers in alkaline soil.

Estimating shadow price for symbiotic nitrogen and technical efficiency for legume‐based conservation agriculture in Malawi

Determining the value of legumes as soil fertility amendments can be challenging, yet this information is required to guide public policy and to incentivise prescribed land‐management practices such as conservation agriculture. We use a directional input distance function (DIDF) to estimate shadow prices for symbiotic nitrogen and the technical efficiency for mixed maize‐legume production systems in Malawi. The shadow prices reflect the trade‐off between fertiliser nitrogen and symbiotic nitrogen required to achieve a given quantity of output. Our results reveal considerable technical inefficiency in the production system. The estimated shadow prices vary across farms and are, on average, higher than the reference price for commercial nitrogen. The results suggest that it would be beneficial to redesign the current price‐support programs that subsidise chemical fertilisers and indirectly crowd‐out organic soil amendments such as legumes.

Bamboo biochar does not affect paddy soil N2O emissions or source following slurry or mineral fertilizer amendment—a15N tracer study

AbstractNitrogen (N)‐containing fertilizers, such as slurry and ammonium nitrate (NH4NO3), can significantly increase soil nitrous oxide (N2O) emissions following addition to agricultural soil. Biochar amendment to soil has been observed to suppress N2O emissions in a number of studies. However, the effect varies depending on many factors, including when biochar is added to soil concurrently with organic or mineral fertilizers. An incubation was conducted in which bamboo biochar (created at 800°C) was added to an ex‐rice paddy soil (1% rate) concurrently with dairy cattle slurry or NH4NO3(100 mg N kg−1). At three time points, following biochar amendment,15N‐labelled NH4NO3(50 mg N kg−1) was added to the soil to determine the N2O emissions derived from nitrification and denitrification in the 24 h that followed (at 70% water filled pore space; days 0, 7, and 28). Nitrous oxide emissions from slurry‐amended soils were much greater than those from NH4NO3‐amended soils, as well as the proportion of soil N2O emissions derived from denitrification. Biochar amendment did not significantly affect soil N2O emissions or consistently affect the percentage of soil N2O emissions derived from nitrification in slurry or NH4NO3‐amended treatments. The lack of N2O‐emission suppression with biochar amendment may have been due to the relatively‐low addition rate of a biochar that had a low content of volatile organic carbons and redox‐reactive organic/inorganic compounds, and did not greatly increase the pH of the acidic soil (pH 5). These results suggest that bamboo biochar produced at such a high temperature may not be suitable for mitigation of soil N2O emissions.

Study of some Morphological Characters in Coconut (Cocos nucifera L.) as Effected by Organic and Inorganic Fertilizers Amendments in Sandy Loam Soil of Karachi, Pakistan

A comparison is made on the effect of organic and inorganic fertilizers on the some morphological characters of coconut. The study demonstrated that the treatments T1 {Nitrogen, Phosphorus and Muriate of potash (NPK) + Neem seed powder (NSP) + Gliricidiasepium leaves (GSL)} and T2 (NPK+ GSL) significantly increased most of the morphological characters (stem girth, number of leaves, petiole and leaflets). The study revealed that vegetatively the coconut was grown well on soil amended with organic and inorganic fertilizers. The morphological characters i.e the stem girth (173.77 cm) of coconut at 20 cm height T1 (NPK + NSP + GSL) treatment produced maximum girth as compared to T2 to T8 {T2 (NPK+ NSP), T3 (NPK+ GSL), T4 (NSP + GSL), T5 (NPK), T6 (GSL), T7 (NSP), T8 (Control)} treatments. The 11 leaf scars length (80.44 cm) was significantly (p&lt;0.05) highest in T1 as compared to T3 to T8 treatments. The present study also revealed that the number of leaves (28.77) were significantly (p&lt;0.05) greater in T1 as compared to T5 to T8 treatments. The petiole length (139.44 cm) and thickness (3.27 cm), were found significantly (p&lt;0.05) highest in T1 as compared to T8 treatment. Leaflets length and number of leaflets were significantly high in T1 and T2 as compared to T3 to T8 treatments while, the leaflets width (5.04 cm) was significantly high in T1 as compared to other treatments. It is therefore, recommended that treatment T1 {NPK (1.0:0.5:1.0kg) + NSP (10.0kg) + GSL (20.0kg)}/palm/year was enough to improve the morphological characters to enhance future productivity.

EFFECTIVENESS OF ORGANIC FERTILIZER AS A BIOSTIMULATING AGENT FOR THE REMOVAL OF NAPHTHALENE IN SOIL

Contamination of the environment by petroleum products such as polycyclic aromatic hydrocarbons (PAHs) is inevitable due to oil production, transportation and distribution activities. The potentials of organic wastes from animal droppings as bioremediation alternative for soils contaminated with naphthalene which is a PAHwas studied. The rate of biodegradation of naphthalene was studied for a period of 28 days under laboratory condition. The result of the microbial counts for soils spiked with 200 mg/kg naphthalene was a total heterotrophicbacteria (THB) count in soil amended with organic fertilizer composted from cattle dung, goat dung, pig dung and poultry manure ranging from 3.53±0.25 to 6.97±0.24 x 10 6 CFU/g. Unamended control soil had THB count ranging from 2.26±0.12 to 2.71±0.22 x 10 6 CFU/g while THB count inunamended autoclaved control soilranged from 1.97±0.02 to 2.22±0.01 x 10 3 CFU/g.The count of total hydrocarbon-utilizing bacteria (THUB) inorganic fertilizer amended soil ranged from 1.7± 0.11 to 4.6±0.18 x 10 5 CFU/g while unamended control soil had THUB ranging from 7.8±0.12 to 9.1±0.14 ×10 4 CFU/g and THUB count in unamended autoclaved control soil ranged from 6.2±0.01 x 10 1 to 2.22±0.04 x 10 3 CFU/g. The percentage naphthalene removal in organic fertilizer amended soil was 70.8%, the percentage naphthalene removal in unamended control soil was 10.1% while the percentage naphthalene removal in unamended autoclaved control soil was 4.6% after 28 days. Evaluation of the first order kinetic model resulted in biodegradation rate constant of 0.292 day -1 and half-life of 2.37days for organic fertilizer amendment of 30 g after 28 days of treatment while unamended control resulted in biodegradation rate constant of 0.011 day -1 and half-life of 63.01 days and unamended autoclaved control resulted in biodegradation rate constant of 0.009 day -1 and half-life of 77.02 days. The results suggest that organic fertilizer supplementation would be effective in the remediation of naphthalene polluted soils. Normal 0 false false false EN-US X-NONE X-NONE

The role of organic/bio–fertilizer amendment on aggregate stability and organic carbon content in different aggregate scales

This study investigated the effects of different organic and bio–fertilizer (alone or in combination) applications on aggregate stability and organic carbon (OC) content in macro (2–1mm) and micro (0.25–0.050mm) aggregate sizes of clay loam (Typic Xerofluvent) textured soil. In addition, correlation between OC content and aggregate stability was determined. The study was conducted as a pot experiment under greenhouse conditions and was arranged in a completely randomized design with three replications. The treatments were: control (no fertilizer) (C), inorganic fertilizer (15:15:15 compound fertilizer+ammonium nitrate, 33% N) (F), mycorrhizal fungi (Glomus spp.) (M), microalgae (Chlorella spp.) (A), bacteria (Bacillus megaterium KBA–10+Pantoea agglomerans RK–134+Pseudomonas fluorescens FDG–37) (BMF), bacteria (Bacillus subtilis PA1+Paenibacillus azotofixans PA2) (BCP), vermicompost (V), vermicompost+mycorrhizal fungi (VM), vermicompost+microalgae (VA), vermicompost+bacteria (VBMF) and vermicompost+bacteria (VBCP) applied in 90days incubation period. At the end of the 90-day incubation period, organic and bio–fertilizer amendments had an increasing impact on aggregate stability and OC content in macro– and micro– aggregate scale. Especially, bio–fertilizers in combination with vermicompost mostly had stronger effects on stability and OC content of aggregates of both size classes in comparison with control and bio–fertilizer treatments alone. In addition, significant (p<0.05) and positive correlations were observed between stability and OC contents of macro (2–1mm) and micro (0.25–0.050mm) aggregates size classes in each treatment.

Tillage, mulch and fertiliser impacts on soil nitrogen availability and maize production in semi-arid Zimbabwe

Conservation agriculture has been promoted widely in sub-Saharan African to cushion smallholder farmers against the adverse effects of soil fertility decline, stabilize crop yields and increase resilience to climate change and variability. Our study aimed to determine if aspects of CA, namely tillage and mulching with manure and fertiliser application, improved soil mineral N release, plant N uptake and maize yields in cropping systems on poor soils in semi-arid Matobo, Zimbabwe. The experiment, run for three seasons (2012/13–2014/15), was a split-split plot design with three replicates. Tillage (animal-drawn ploughing and ripping) was the main plot treatment and residue application was the sub plot treatment with two levels (100% residues removed or retained after harvest). Five fertility amendments (mineral fertiliser at 0, 20 and 40kgN ha-1, 5tha-1 manure only and 5tha-1 manure+20kgNha-1) were sub-sub plot treatments. Plough tillage stimulated N mineralisation by 4–19kgNha-1 and maize N uptake 13–23% more than the ripper tillage. When mulch was added to the plough tillage, mineralisation was slowed resulting in less crop N uptake (by 5–19%) compared with no mulch application. N uptake was highest in the manure treatments. N recovery and agronomic N efficiency by maize were highly variable over the three seasons, reflecting the uncertainty complicating farmers’ decision making. Nitrogen recovery in the manure treatments was generally poor in the first season resulting in low grain yields in the range 100–260kgha-1 regardless of tillage, though higher in subsequent seasons. In the second season manure application gave the largest grain yields under the ripper tillage, both with and without mulch averaging 1850 and 2228kgha-1 respectively. Under the plough tillage, the 40kgNha-1 treatment gave the highest grain yields of 1985kgha-1. In the third season yields were generally poor under all treatments due to low and poorly-distributed rainfall. The CA principles of minimum soil disturbance and maintenance of a permanent mulch cover resulted in reduced soil mineral N availability for crop uptake and poor maize yields. Nutrient inputs through mineral fertilisers and manure are key to ensuring production in such infertile, sandy soils which predominate in semi-arid regions of southern Africa.

Organic and inorganic fertilizer amendments on sustainable health of garden pea (Pisum sativum L.)

The study was conducted to assess the growth, yield and quality of pea under different fertilizer amendments. the results of the growth and yield attributing characters, viz., seed per pod (7.58), seed per plant (52.75), shelling % (50.33%), fresh biomass (33.58 g), dry biomass (10.59 g), pod yield per plant (40.88 g) and pod yield per hectare (9.20 t ha−1) were significantly highest in T3. while plant height (56.25 cm) and pod per plant (7.13) were highest in t2. Similarly, t2 also recorded the highest quality characters, viz., tSS (14.63 oBrix), crude protein (22.06%), ash content (3.70%), ascorbic acid (9.52 mg 100g−1 Fw) and β-carotene (274.24 μg g−1 Fw). Number of branch, days to 50% flowering, pod length and pod diameter were found non-significant. The economics analysis indicated that T2 gave maximum benefit cost ratio of 3.50.