Soil and crop responses following application of biosolids-derived organomineral fertilisers to ryegrass (Lolium perenne L.) grown in pots

Biosolids-derived organomineral fertilisers (OMF) were produced using a novel technique reported in earlier studies. This technique enables addition of N and potash to biosolids granules to form a balanced NPK fertiliser. Two fertiliser products; OMF10 (10:4:4) and OMF15 (15:4:4), were formulated and tested in a glasshouse facility on pot-grown ryegrass in comparison with urea and biosolids granules at N application rates ranging from 0 to 300 kg ha-1. The aim of this research was to contribute to the understanding of nutrients management and dynamics in grass crops fertilised with OMF. The study focused upon dry matter yield (DMY) and crop responses to applied fertiliser, nitrogen use efficiency (NUE) and fertilisers’ effect on soil fertility. Results indicated that ryegrass responds linearly to application of OMF increasing DMY by about 2% to 27% compared with biosolids but to a lesser extent than urea (range: 17% to 55%). NUE was related to the concentration of readily available N in the fertiliser; urea and OMF showed significantly greater (P<0.05) N recoveries than biosolids (26% to 75%, and 19% to 29%, respectively). Total nitrogen in soil and SOM increased (P<0.05) depending on the concentration of organic-N in the fertiliser applied. DMY was lower but more sustained overtime in biosolids-treated pots. OMF application did not result in significant changes in soil extractable-P levels whereas for urea, it decreased significantly while it showed a significant increase in biosolids-treated pots, where soil-P Index changed from 5 to 6. In OMF-treated soil, soil P Index remained close to constant overtime thereby supporting the purpose of the formulations tested

Phosphorus Release Characteristics from Biosolids-Derived Organomineral Fertilizers

This study investigated the availability of phosphorus (P) following soil application of a novel biosolids-derived organomineral fertilizer (OMF15; 15:4:4) in comparison with single superphosphate (0:18:0). Two soil types of contrasting characteristics were incubated over a period of 90 days at 25 °C and maintained near field capacity. Phosphorus was applied at rates equivalent to 0 (control), 150, and 300 kg ha−1 of P2O5, respectively. Availability of P from OMF15 was low throughout the experiment accounting for less than 6.5% of total OMF15-P applied. It was shown that after the 90 days incubation period, the overall increase in soil extractable P in OMF15-treated soil was marginal in both soil types. For single superphosphate (SSP), P availability ranged from 16% to 46% of total SSP-P applied. Application of SSP increased soil extractable P levels significantly (P < 0.001) compared with unfertilized control soils. The results of this study aided the development of fertilization strategies for the best use of OMF produced from nutrient-enriched biosolids granules for applications in winter cereal and grass crops in England

Nitrogen release characteristics from biosolids-derived organomineral fertilizers

is study investigated the availability of nitrogen (N) following soil application of a novel biosolids-derived organomineral fertilizer (OMF15—15:4:4) in comparison with urea (46% N). OMF15 is produced by coating biosolids granules (particle size range: 1.10–5.50 mm in diameter) with urea and potash [60% potassium oxide (K2O)], which increase the concentration of mineral N and potassium (K), respectively, resulting in a balanced fertilizer material suitable for application in cereal and grass crops. The study comprised two soil types of contrasting characteristics which were incubated over a period of 90 days at 25 °C and maintained near field capacity. Nitrogen was applied at rates equivalent to 0 (control), 150, and 300 kg ha−1, and soil mineral N measured routinely using standard laboratory techniques. Results showed that the majority of N was released from OMF15 within 30 days from application (range: 40% to 72% of total OMF15-N applied) with a further 10% to 28% in the following 60–90 days. OMF15 required an accumulated thermal time of 2250 degrees-day to release between 68% and 79% of the total OMF15-N applied. From this, it was inferred that mineralization of the organic-N fraction in OMF15 is likely to progress beyond harvest of winter cereal crops in-field conditions in England. The results of this study aided the development of fertilization strategies for the best use of OMF in winter cereal and grass crops

Ten-year legacy of organic carbon in non-agricultural (brownfield) soils restored using green waste compost exceeds 4 per mille per annum: Benefits and trade-offs of a circular economy approach

Soil organic carbon (SOC) was re-analysed 10 years after application of source-segregated green waste compost at a 1 ha previously-developed UK site to compare with the increases suggested by the 4 per mille initiative proposed at COP21 in Paris. Compost prepared to PAS100 standard had been incorporated once at rates of 250, 500 and 750 t·ha−1 in 2007 in clay subsoil prior to planting of perennial energy crops. Our results show statistically significant differential increases in SOC, total nutrients N and P, or contaminants Zn, Pb, Cu, As and B, remain from the compost application after a decade. For the 500 or 750 t·ha−1 compost rates the SOC increments in the upper 10–15 cm were 0.85% or 1.6% over the 4.9% developed from a baseline of 1.8% in control areas by a decade of natural regeneration. Calculation of the elemental loadings from the compost analyses compared to the present-day levels suggests SOC declines after application at an average annual rate approaching 10%, compared to 5% for the nutrients or contaminants, roughly equivalent to half-lives of 5 or 10 years respectively. The study demonstrates the long-term soil organic matter (SOM) additions, fertility benefits and technical feasibility of a one-off, high-rate application of waste-derived compost to improve urban soils, compared to the potential trade-off of adding to PTE loadings. This longevity of SOC addition, previously unrecognised in brownfield soils, may be inferred for other areas where further cultivation is precluded, as is typical after landscape restoration or under perennial energy crops for the production of biomass. This unprecedented result has wider implications for marginal land use for bioenergy and the opportunities therein for SOC management using anthropogenic organic wastes to mitigate greenhouse gas emissions

Impact of crude oil on yield and phytochemical composition of selected green leafy vegetables

Total petroleum hydrocarbons (TPH) cleanup standards, intervention and/or target values, are designed to effectively manage introduction of toxic petroleum hydrocarbons into the environment. This research assessed the impact of some crude oil remediation intervention values (CRIV), involving sublethal concentrations of crude oil, on yield and phytochemical contents of kale (Brassica oleracea L.) and lettuce (Lactuca sativa L.). Crude oil contamination within the range examined did not affect emergence; yield and phytochemical distributions were affected at some levels of contamination, particularly 10000 mg·kg−1 TPH. There is the potential of TPH to moderate effects of crude oil at 10000 mg·kg−1 to enhance contents of some phenolics and organic acids in green leafy vegetables, but it causes accelerated maturity and leaf senescence. Use of CRIV below 10000 mg·kg−1 TPH appears to be effective

Opportunities and challenges organo-mineral fertiliser can play in enabling food security

Food security is a growing challenge related to an increasing global population. The agricultural sector is key for a secure supply of food but relies up to 50% on mineral fertilisers to meet crop nutrient demands. As mineral fertilisers production is energy intensive, causing close to 2% of global greenhouse gas (GHG) emissions, this poses greater challenge to meet net zero targets. Other challenges include extreme weather patterns, GHG during fertiliser applications and diffuse pollution, declining soil health, pest, disease, and loss of soil biodiversity. As mineral fertilisers’ price increases and the state of soil health decreases, innovative solutions are needed to meet crop nutrient demands while ensuring that sufficient organic matter is conserved in the soil. One solution to achieve net zero in agriculture can be in the form of organo-mineral fertilisers (OMF). OMFs are a new concept that take organic feedstock (such as biosolids, livestock manure, crop residues, food waste) and combines them with reduced amounts of mineral fertilisers resulting in a balanced fertiliser product. This Perspective piece discusses a Strength-Weakness-Opportunities-Threats (SWOT) analysis on OMF and summarizes how OMF applications can play a role to improve food security. This is further linked with short, medium and long terms policy interventions that can be deployed to achieve a more sustainable approach by balancing between protecting the wider environment and meeting food security.The author would like to acknowledge funding received from UKRI Innovate UK Defra Farming Innovation Programme (10026016). The policy aspect of this work was carried out as part of a separate project that received the Research England Policy Support Fund

Understanding the impacts of crude oil and its induced abiotic stresses on agrifood production: a review

In many parts of the world, the agricultural sector is faced with a number of challenges including those arising from abiotic environmental stresses which are the key factors responsible for most reductions in agrifood production. Crude oil contamination, an abiotic stress factor and a common environmental contaminant, at toxic levels has negative impacts on plants. Although various attempts have been made to demonstrate the impact of abiotic stresses on crops, the underlying factors responsible for the effects of crude oil and its induced abiotic stresses on the composition of the stressed plants are poorly understood. Hence, this review provides an in-depth examination of the: (1) effect of petroleum hydrocarbons on plants; (2) impact of abiotic environmental stresses on crop quality; (3) mechanistic link between crude oil stress and its induced abiotic stresses; as well as (4) mode of action/plant response mechanism to these induced stresses. The paper clearly reveals the implications of crude oil-induced abiotic stresses arising from the soil-root-plant route and from direct application on plant leaves

Phosphate acceptance map: A novel approach to match phosphorus content of biosolids with land and crop requirements

Phosphorus is a key irreplaceable nutrient that plays a major role in crop nutrition. The mineral form of phosphorus fertiliser is a mined resource and its supply comes predominantly from geopolitically sensitive parts of the world. A renewable source of phosphorus such as biosolids therefore offers a sustainable option. Nevertheless, continuous application of biosolids needs to be managed to ensure that soil is not saturated with nutrients which can then become a cause for concern in terms of enrichment of water bodies in the event of an erosion. Existing field trials have demonstrated the efficacy of biosolids as phosphorus fertiliser to meet crop demand whilst maintaining an environmentally safe amount in the soil. However, field trials are expensive, and an alternative would be a geospatial tool that builds on such information to act as a decision support tool to determine suitability of land to receive biosolids whilst ensuring that phosphorus levels are in environmentally safe limits. Thus, a novel and evidence-based decision support method for assessing land suitability for biosolids application at a national scale known as the Phosphate Acceptance Map (PAM) is described here. It provides a sound basis for addressing this need, layering over the model the means to capture a range of realistic scenarios, developed with industry practitioners, to allow exploration of the consequences of different land management strategies. The research method has involved the development and application of a modelling approach for phosphate acceptance, drawing from a collation of the core geographical and descriptive data themes required. These data describe both the environmental characteristics of the land under assessment, as well as the expression of nominal stakeholder values and protected areas. In considering the methods, it may be noted that the modelling drew upon key empirical data themes as a pragmatic approach. A number of key national datasets have been utilised such as the National Soil Map (Natmap), the ‘National Soil Inventory’ (NSI), geology and land use, as well as topography and prevailing climatic data. Demographic data was used to calculate potential arising nationally which was coupled together in the context of fertiliser recommendations. The issues addressed in the PAM modelling span borders and thus, where the data required is forthcoming, the methods demonstrated also have the potential to support wider application in other national contexts

Reusing oil and gas produced water for irrigation of food crops in drylands

Water scarcity severely affects drylands threatening their food security, whereas, the oil and gas industry produces significant and increasing volumes of produced water that could be partly reused for agricultural irrigation in these regions. In this review, we summarise recent research and provide a broad overview of the potential for oil and gas produced water to irrigate food crops in drylands. The quality of produced water is often a limiting factor for the reuse in irrigation as it can lead to soil salinisation and sodification. Although the inappropriate use of produced water in irrigation could be damaging for the soil, the agricultural sector in dry areas is often prone to challenges in soil salinity. There is a lack of knowledge about the main environmental and economic conditions that could encourage or limit the development of irrigation with oil and gas effluents at the scale of drylands in the world. Cheaper treatment technologies in combination with farm-based salinity management techniques could make the reuse of produced water relevant to irrigate high value-crops in hyper-arid areas. This review paper approaches an aspect of the energy-water-food nexus: the opportunities and challenges behind the reuse of abundant oil and gas effluents for irrigation in hydrocarbon-rich but water-scarce and food-unsecured drylands

Realizing the circular economy for sanitation: assessing enabling conditions and barriers to the commercialization of human excreta derived fertilizer in Haiti and Kenya

Efficient fecal sludge management solutions are especially challenging in densely populated urban informal settlements, where space is limited and land tenure uncertain. One solution is to collect and treat human excreta to produce soil conditioners for use in agriculture, through container-based sanitation, thus realizing the circular economy for sanitation. This study focused on container-based sanitation ventures that produce and sell fertilizers from human excreta. Stakeholder interviews showed that challenges faced by these ventures were similar: unclear regulations on the use of fertilizers derived from source-separated excreta, undeveloped markets for organic fertilizers, difficulties in securing secondary sources of organic matter for composting as well as complex transport and distribution logistics. The findings of this study emphasized the need for clear policies with respect to human excreta derived fertilizer, as well as institutional involvement in order to incentivize the sale and use of human excreta derived fertilizer locally to ensure that sustainable and safely managed sanitation systems are available in urban areas