Sustainable Nutrient Research Articles

How economic instruments address sustainable nutrient use: the example of phosphorus governance

BackgroundThe widely inefficient agricultural use of phosphorus (P) causes environmental damage. At the same time, an uneven resource distribution risks supply shortages for this essential nutritional element. Effective governance solutions help to stimulate a more sustainable P management and fulfil the human right to food. This article applies a qualitative governance analysis to develop an integrated governance solution for the multi-layered problems of agricultural P use primarily by economic instruments. Based on P-related challenges and the cornerstones of sustainable P management, an assessment scheme for economic instruments for P is conceptualized and applied.ResultsResults show that there is no ‘one fits all’ solution for all problems associated with agricultural P use. We find a combination of (1) an economic instrument for rock phosphate-based fertilizers with (2) a tax for P surpluses and (3) a regulation on contaminant levels in fertilizers addresses all P-related problems effectively.ConclusionsThe optimal P governance combines economic and regulatory policy instruments. Besides addressing sustainable P management and thus contributing to the implementation of the right to food, the policy mix also positively impacts further ecological challenges such as disrupted N cycles, climate change and biodiversity loss.

Synergistic Impact of Biochar and Organic Amendments on Field Bean (Vicia faba) Growth and Soil Characteristics

Many studies have explored the effects of various biochar types and their combinations with inorganic fertilizers, but few have focused on identifying the most effective organic amendments when used with biochar in sandy loam soil. This study aims to determine the impact of different biochar doses combined with organic amendments on plant growth and yield (Vicia faba) in sandy loam soil. Biochar doses of 15, 20, and 25 t/ha were applied in combination with organic amendments such as farmyard manure (FYM), vermicompost (VC), Ghanajeevamruth (GA), and their various combinations. The effectiveness of these treatments was compared to the use of biochar alone. Results indicated that the combination of biochar and organic amendments significantly increased average pod number (by 36.19% to 88.63%) and pod weight (by 24.11% to 83.18%) compared to biochar alone. Higher biochar doses consistently resulted in increased pH levels in the soil, regardless of the organic amendment used. Additionally, biochar combined with organic amendments led to higher nutrient levels, including nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur, compared to biochar alone. The study concluded that biochar, particularly in combination with Ghanajeevamruth, had superior effects on plant growth and yield. The choice of amendment and biochar dose significantly influenced soil pH, nutrient availability, bulk density, and water holding capacity. These findings confirm the potential of combining biochar with organic amendments to enhance soil fertility and agricultural productivity, offering valuable strategies for sustainable nutrient management in sandy loam soils.

Silicon as a Predicator of Sustainable Nutrient Management in Maize Cultivation (Zea mays L.)

Field trials were conducted at the Field Experimental Station in Winna Góra. Weed control after maize sowing increased the grain yield by 15.7% compared to that after herbicide application at the BBCH 14/15 stage. Higher effectiveness of silicon application in maize cultivation can be achieved on plantations free from primary or secondary weed infestation. The application of a 50% NPK dose increased the grain yield by 8.6%, while a 100% dose improved it by 13.9% compared to that of the control object (without mineral fertilization). Furthermore, it was observed that the effectiveness of the silicon increased with higher total precipitation during the maize growing season, as evidenced by the results from 2022. In that year, the difference between the control (without silicon application) and the treatment with silicon applied at the BBCH 15/16 stage was more than 33%. The average mass losses from the green tea bags ranged from 54.9% to 71.9% in the variant of the sowing experiment carried out after spraying with the herbicide and from 69.4% to 72.4% in the variant with herbicide spraying at the BBCH14 stage. The rooibos tea’s mass losses were lower, as expected, and ranged from 18.6% to 36.4% in the first variant and from 30.8% to 38.6% in the second variant. The mass losses of the green tea and rooibos tea were the highest in the variant with herbicide spraying at the BBCH14 stage and the lowest in the variant of the sowing experiment carried out after herbicide spraying. The stabilization factor (S) ranged from 193 × 10−3 to 254 × 10−3 in sowing after herbicide spraying and from 188 × 10−3 to 226 × 10−3 in the variant with herbicide spraying at the BBCH14 stage. The k (decomposition constant) ranged from 7.8 × 10−3 to 11.5 × 10−3 in the first variant and from 7.2 × 10−3 to 13.4 × 10−3 in the variant with herbicide spraying at BBCH14.

Evaluating the Impact of Phosphorus and Solid Oxygen Fertilization on Snap Bean (Phaseolus vulgaris L.): A Two-Year Field Study.

The snap bean (Phaseolus vulgaris L.) is highly sensitive to both phosphorus (P) deficiency and hypoxic stress, which together can significantly hinder plant growth, nutrient uptake, and yield; however, limited information exists on the effect of P and oxygen (O2) fertilization to alleviate these stresses and enhance yield. A two-year field experiment assessed the effects of P and O2 fertilization on plant growth, pod yield, and P uptake in acidic sandy soil. Using a randomized complete block design with four replications, we tested five P rates (0, 45, 90, 135, and 179 kg ha-1 of phosphorus pentoxide, P2O5) in the form of triple superphosphate (TSP) along with two rates (0 and 45 kg ha-1) of solid O2 fertilizer as calcium peroxide (CaO2). Phosphorus and O2 fertilizers improved plant growth and pod yield, with the highest yield from the combination of 135 kg ha-1 P2O5 and 45 kg ha-1 CaO2. Pearson correlation analysis indicated strong associations between plant growth, pod yield, and nutrient accumulation. Principal component analysis (PCA) highlighted notable seasonal differences in snap bean and soil characteristics. This study provides essential insights into the use of O2 fertilizers as a cost-effective approach to mitigate hypoxia, enhance P use efficiency, and improve yield in snap bean. Our findings may inspire the development of sustainable nutrient protocols for high-quality snap bean production and serve as a foundation for similar applications in other crops.

Sustainable nutrient management and agricultural productivity in chernozem soils of the Kostanay Region, Kazakhstan

Chernozem soils, known for their high organic matter and fertility, are crucial for agricultural productivity in northern Kazakhstan's Kostanay region. This study evaluated the physical, chemical, and biological properties of these soils to assess their suitability for crop production and propose sustainable management practices. Soil samples were collected from 0-20 cm depths across various locations to represent the region's main nutrient profile. Physical analyses included texture determination, while chemical analyses measured pH, electrical conductivity (EC), organic matter, and nutrient levels (N, P, K, Ca, Mg, Fe, Cu, Zn, and Mn) using standard methods. Biological assessments focused on microbial biomass carbon (Cmic), basal soil respiration (BSR), dehydrogenase and catalase activities, as well as Cmic: Corg and metabolic quotient (qCO₂) ratios. Results indicated high organic matter content (mean 4.49%), sufficient total nitrogen (>0.25%), and high levels of potassium and calcium. However, phosphorus levels were low (

Exploring oil cakes in the production of proteases: a systematic review

Oil cakes, valuable co-products of the oil industry, are rich in bioactive and nutritional compounds, making them suitable for biotechnological processes that lower costs and reduce environmental impact. These versatile materials are commonly used as substrates for microbial enzyme production, particularly in the context of sustainable, cost-effective protease synthesis. This review surveyed the application of oil cakes as substrates for microbial protease production, focusing on studies published between 2013 and 2023 from databases such as ScienceDirect, PubMed, Web of Science, and Scopus. After screening, 30 studies were deemed eligible from an initial pool of 1602 articles. Nineteen different oil cake types were identified, with soybean cake being the most utilized. The studies highlighted the effectiveness of oil cakes in supporting microbial protease production, particularly with species from the Aspergillus (fungi) and Bacillus (bacteria) genera. Despite the diversity of microorganisms and substrates explored, only a limited number of studies provided detailed compositional analyses of the oil cakes. Nonetheless, the review underscores the growing trend of using oil cakes as an economical and sustainable nutrient source for microbial protease production. Oil cakes, valuable co-products of the oil industry, are rich in bioactive and nutritional compounds, making them suitable for biotechnological processes that lower costs and reduce environmental impact. These versatile materials are commonly used as substrates for microbial enzyme production, particularly in the context of sustainable, cost-effective protease synthesis. This review surveyed the application of oil cakes as substrates for microbial protease production, focusing on studies published between 2013 and 2023 from databases such as ScienceDirect, PubMed, Web of Science, and Scopus. After screening, 30 studies were deemed eligible from an initial pool of 1602 articles. Nineteen different oil cake types were identified, with soybean cake being the most utilized. The studies highlighted the effectiveness of oil cakes in supporting microbial protease production, particularly with species from the Aspergillus (fungi) and Bacillus (bacteria) genera. Despite the diversity of microorganisms and substrates explored, only a limited number of studies provided detailed compositional analyses of the oil cakes. Nonetheless, the review underscores the growing trend of using oil cakes as an economical and sustainable nutrient source for microbial protease production.

Spent coffee ground biochar for phosphate adsorption in water: Influence of pyrolysis temperature and iron-coating activation method

A substantial portion of the phosphorus utilized in crop and food production is dispersed into soil and water, posing a challenge to the management of eutrophication and sustainable nutrient recovery. This research focuses on the reclamation of phosphate from polluted water through affinitive adsorption on biochar derived from spent coffee grounds (SCG). SCG were subjected to pyrolysis within a N2-purged vertical furnace across a temperature range of 300–550 °C, with a 1-h holding time. The adsorption capability of SCG biochar was systematically investigated and experimental data were interpreted using Langmuir and Freundlich isotherm models. Notably, the biochar pyrolyzed at 450 °C and activated with a Fe/biochar mass ratio of 2:1 demonstrated the highest adsorption capacity (0.87 mg P/g biochar) when exposed to the highest initial phosphate concentration in the solution (15 mg P/L). Comparative analyses revealed that the removal efficiency of non-activated SCG biochar was considerably lower (5.7%) compared to the corresponding activated biochar (up to 17.3%). This highlights the significant increase in adsorption capacity facilitated by the introduction of ferric chloride. Furthermore, phosphate desorption experiments were conducted to assess the biochar's phosphorus release characteristics and stability. The results demonstrate the positive outcomes of upcycling SCG waste material as a pollutant sorbent and the potential to diminish reliance on chemical fertilizers through the recovery of Fe-phosphate-enriched SCG biochar.

Effects of additives on shifting phosphorus to solid phase during Solid-Liquid separation of digestate in full-scale biogas plant

Phosphorus (P) is critical for plant growth, but global reserves are exhausting within 250–300 years, therefore enhancing phosphate recycling is crucial for the future. Biogas digestate, rich with nutrients is a promising resource for nutrient recovery. Conventional solid–liquid separation shifts approximately 35 % of the total P in the digestate to the solid phase. Separation trials with additive treatment using a screw press with a 0.75 mm sieve were performed at University of Hohenheim’s full-scale biogas plant. After 22 h, 67.41 % (kieserite treatment) and 52.35 % (strawflour treatment) of total P shifted to the solid phase. Treatment with kieserite enhanced P shift into the solid phase by forming non-labile fractions through a chemical bond between P and Mg2+ ions. Kieserite treatment for 22 h effectively increases the share of total P in the separated solid phase, it also ensures a sustainable nutrient supply and mitigates the risk of nutrient runoff.

Enhanced phosphorus availability and cadmium remediation using phosphate-solubilizing bacteria-loaded biochar in contaminated soils

Phosphate-solubilizing bacteria (PSB) have garnered extensive attention for their ability to improve soil phosphorus (P) availability and their potential applications in bioremediation. However, the efficacy of PSB is contingent upon their colonization in soils, which can be hindered by the toxicity of heavy metals such as cadmium (Cd). Utilizing biochar as a protective carrier for PSB presents a promising strategy to address this challenge. This study investigated the effects of PSB-loaded biochar on soil P pools and wheat (Triticum aestivum L.) growth under Cd-contaminated conditions. Results indicated that biochar loading facilitated the colonization and functioning of the inoculated PSB strain (Bacillus subtilis), as evidenced by increased soil cultivatable PSB abundance and phosphatase activity as well as increased relative abundance of Bacillus in bacterial community. Consequently, improved soil P availability and reduced soil exchangeable Cd content were observed, leading to a 30.3 % increase in wheat shoot biomass, a 50.4 % increase in P accumulation, and a 24.1 % reduction in Cd accumulation in wheat shoots under the PSB-loaded biochar treatment. Significant shifts in bacterial community composition were revealed by 16S rRNA amplicon sequencing and enhanced microbe-mediated metabolic activities were observed, as demonstrated by soil enzyme assays and metabolome analysis. Overall, these findings underscore the potential of PSB-loaded biochar to enhance P availability, mitigate Cd toxicity, and shape the soil microbial community, offering a promising strategy for sustainable nutrient management and bioremediation in Cd-contaminated agricultural soils.

Hydroponic Lettuce Cultivation with Organic Liquid Fertilizer: Examining Bacterial Inhibition and Phosphate Solubilization

This study explores organic hydroponic cultivation as a sustainable alternative to chemical fertilizers amid global supply challenges. With rising costs and the depletion of conventional nitrogen sources, organic liquid fertilizers are gaining attention for their microbial enrichment processes (MEP) that convert organic matter into plant-accessible nutrients. This experiment focuses on lettuce cultivation using two organic liquid fertilizers, Power Fish and POF vol. 2, in controlled environments. The results show that there are significant differences in plant growth parameters such as leaf number, fresh weight, chlorophyll content, and root length across different fertilizer treatments. Key findings include that effective management practices, including pH control and regular nutrient application, are crucial for maintaining microbial activity and optimizing nutrient uptake efficiency. Additionally, Bacillus sp. and Xanthomonas sp. were isolated from these fertilizers and dual-cultured with rot fungi, Pythium sp. and Fusarium sp. This dual cultivation demonstrated inhibitory activity against these pathogens, showcasing the potential of these microorganisms in promoting biofilm-mediated disease resistance in organic hydroponic systems. The study also emphasizes the phosphate solubilization capabilities of isolated bacteria, essential for sustainable nutrient cycling. Overall, organic hydroponic systems present a promising strategy for sustainable agriculture, reducing dependency on chemical inputs while enhancing crop productivity and resilience to environmental stressors.

Potential of a novel brine-struvite-based growth medium for sustainable biomass and phycocyanin production by Arthrospira platensis.

Nutrient recovery is crucial for sustainability as it helps to recycle valuable resources, reduce environmental pollution, and promote the efficient use of natural materials in various agricultural and industrial processes. The present study investigated the impact of using brine and struvite as sustainable nutrient sources on the growth and c-phycocyanin (C-PC) production by the cyanobacterium Arthrospira platensis. Three modified growth media were compared to the standard SAG-spirul medium under yellow-white light [YLT], and blue-white light [BLT]. In the modified medium BSI, a struvite solution was utilized to replace dipotassium phosphate, while diluted brine was used to replace NaCl and de-ionized H2O. For BSII, struvite and brine were used as in BSI, with elimination of the micronutrient from the solution. In BSIII, no other nutrient sources than bicarbonate-buffer were used in addition to struvite and brine. For each medium, A. platensis was cultivated and incubated under YLT or BLT till the stationary phase. The results showed that the combinations of brine and struvite did not have any significant negative impact on the growth rates in BSIII. However, adding struvite as a phosphorus source boosted C-PC production just as effectively as YLT, with boosting biomass yield, unlike when only BLT was used. In conclusion, the brine/struvite-based media resulted in high biomass productivity with higher C-PC yields, making it an ideal growth medium for commercial sustainable C-PC production.

Effect of Feed on the Growth Performance, Nutrition Content and Cost of Raising the Field Cricket (Gryllus madagascarensis) as a Sustainable Nutrient Source in Madagascar.

The field cricket, Gryllus madagascarensis, is a sustainable and nutritious food resource that has the potential to mitigate global malnutrition. Feeds provided to this cricket can influence its growth parameters, nutritional content, and the cost of raising it for food. The current study aimed to evaluate the effects of feeds formulated from weeds, agro-byproducts, and chicken feed (control) on the growth parameters and nutritional content of G. madagascarensis. The formulated feeds included CFB (25.0% protein), CFC (24.5% protein), CFD (24.0% protein), CFE (23.5% protein), CFF (22.5% protein), CFG (21.5% protein), CFH (20.0% protein), CFI (14.5% protein), and CFJ (13.5% protein), and chicken feed (CFA) (28% protein) was used as the control. The formulation of the feeds was based on the acceptability and protein content of the 12 selected weeds and agro-byproducts. Proximate, mineral, and fatty acid analyses were conducted to determine the nutrient content of each feed, as well as the crickets raised on these feeds. The fastest development time was recorded with CFE and CFC. The highest survivorship (98%) was observed in CFG, CFE, and CFC. The highest body mass (1.15 g) and body length (26.80 mm) were observed in crickets fed CFG. By comparison, crickets fed control feed averaged a body mass of 0.81 g and a body length of 23.55 mm. The feed conversion ratio for G. madagascarensis fed CFG, CFE, and CFC was 1.71. Crickets raised on CFH and CFG had the lowest cost of feeding per kg live mass gain. Crickets fed on CFF had the highest quantity of protein (67%), followed by those fed CFG (65% protein); crickets with the lowest protein content (50%) were fed CFJ. Crickets fed on CFG had the highest mineral content. Linoleic acid, oleic acid, and palmitic acid were the major fatty acids. The findings indicate that formulated feeds from weeds and agro-byproducts have great potential to be used as an alternative feed source for crickets for two reasons: their capacity to positively influence the biology and nutrition of the cricket, and they can serve as an inexpensive replacement for chicken feed.

Insight into the preparation and improved properties of cellulose citrate ester hydrogel slow-release fertilizer

The development of new fertilizers with significant water retention capacity and sustainable nutrient supplementation for arid and semi-arid regions remains an important challenge. In this study, a novel slow-release fertilizer (CCEH-SRF) based on cellulose citrate ester (CCE), which is low-cost and biocompatible, was developed using epoxy chloropropane (ECH) as a cross-linker and urea as a fertilizer. The CCEH-SRF exhibited higher water swelling (21.58 g·g−1) and water retention capacity (20.69 % in 7 days) compared to the neat cellulose hydrogel (CH). Furthermore, the CCEH-SRF demonstrated improved release performance with cumulative slow-release rates of 48.0 % at 2 hours in water, and 5.3 %, 65.9 %, and 66.7 % after 1 day, 26 days, and 35 days respectively in simulated soil column percolation assays, whereas the CH-based SRF had inferior release performance. The nutrient slow-release of CCEH-SRF followed the First-order kinetic model and Fick diffusion process accurately. Additionally, the developed CCEH-SRF showed positive growth promotion effects on maize seedlings, indicating its promising practical applicability. Therefore, this work provides a novel approach for developing environmentally friendly SRFs by utilizing natural cellulose derivatives from readily available agricultural waste in fields such as waste reuse, sustainable agriculture, and horticulture.

Sustainable nutrient recovery through struvite precipitation from poultry and multi-substrate agricultural waste digestates

This study addresses the multifaceted challenges stemming from the excessive application of manure or digestate, with the aim of mitigating problems of storage, emissions, contamination and transportation. It presents a unique-protocol for efficiently recovering nutrients in the form of struvite, a pure, easy-to-use magnesium ammonium phosphate compound. The objective is to explore struvite production via mono-digestion of poultry manure and co-digestion of various organic wastes, including poultry, dairy, pig manures, and wasted corn silage. Crystals are synthesized under optimized conditions: magnesium/phosphorus ratio of 1.5, pH 9, and mixing at 240 rpm. The process achieves ≥95 % TAN-recovery in moisture-free form for various digestates, with a significant 61.5 % reduction in volatile-fatty-acids. Approximately 0.33–1 g struvite is produced per 10 mL digestate. The study suggests using disodium or monopotassium phosphate for practical implementation, demonstrating the versatility of digestates. Integrating this method into anaerobic digestion promotes the circular-economy and sustainable management of waste nutrients.

Advanced electrochemical membrane technologies for near-complete resource recovery and zero-discharge of urine: Performance optimization and evaluation

The depletion of nutrient sources in fertilizers demands a paradigm shift in the treatment of nutrient-rich wastewater, such as urine, to enable efficient resource recovery and high-value conversion. This study presented an integrated bipolar membrane electrodialysis (BMED) and hollow fiber membrane (HFM) system for near-complete resource recovery and zero-discharge from urine treatment. Computational simulations and experimental validations demonstrated that a higher voltage (20 V) significantly enhanced energy utilization, while an optimal flow rate of 0.4 L/min effectively mitigated the negative effects of concentration polarization and electro-osmosis on system performance. Within 40 min, the process separated 90.13% of the salts in urine, with an energy consumption of only 8.45 kWh/kgbase. Utilizing a multi-chamber structure for selective separation, the system achieved recovery efficiencies of 89% for nitrogen, 96% for phosphorus, and 95% for potassium from fresh urine, converting them into high-value products such as 85 mM acid, 69.5 mM base, and liquid fertilizer. According to techno-economic analysis, the cost of treating urine using this system at the lab-scale was $6.29/kg of products (including acid, base, and (NH4)2SO4), which was significantly lower than the $20.44/kg cost for the precipitation method to produce struvite. Excluding fixed costs, a net profit of $18.24/m3 was achieved through the recovery of valuable products from urine using this system. The pilot-scale assessment showed that the net benefit amounts to $19.90/m3 of urine, demonstrating significant economic feasibility. This study presents an effective approach for the near-complete resource recovery and zero-discharge treatment of urine, offering a practical solution for sustainable nutrient recycling and wastewater management.

Microbial nutrient recovery cell as an efficient and sustainable nutrient recovery option in sewage treatment

Globally, nutrient pollution is a serious and challenging concern. Wastewater treatment plants (WWTPs) are designed to prevent the discharge of contaminants resulting from anthropogenic sources to the receiving water bodies. In this study, seasonal nutrient pollution load, and biological nutrient removal efficiency of an anoxic aerobic unit based WWTP were investigated. Seasonal assessment revealed that the average total nitrogen removal efficiency and total phosphorus removal efficiency of the WWTP do not meet the discharge standard of 10 mg/L and 1 mg/L, respectively. Furthermore, the WWTP does not utilize the energy contained in the wastewater. In this regard, dual chamber MFC (D-MFC) has emerged as a promising solution that can not only treat wastewater but can also convert chemical energy present in the wastewater into electrical energy. However, higher N O3− (57 ± 4 mg/L) and P–P O43− (6 ± 0.52 mg/L) concentration in cathodic effluent is a major drawback in D-MFC. Therefore, to solve this issue, D-MFC was transformed into a microbial nutrient recovery cell (MNRC) which demonstrated a final N H4+-N and P–P O43− concentration of nearly 1 mg/L with N H4+-N and P–P O43− recovery up to 74 % and 69 %, respectively in the recovery chamber. Besides, MNRC attained a maximum power density of 307 mW/m3 and a current density of 1614 mA/m3, thus indicating MNRC is an eco-friendly, energy-neutral, and promising technology for electricity generation and recovering nutrients.

Transforming waste to wealth: Impact of food waste‐derived soil amendments and synthetic nitrogen fertilizer on soil dynamics

AbstractApproximately one‐third of all food produced globally goes to waste, highlighting the need for sustainable waste management technologies like composting and anaerobic digestion. These technologies convert food waste into soil amendment products such as compost, liquid digestate (LD) and solid digestate (SD). However, these food waste‐derived soil amendments have relatively low nutrient contents compared with synthetic nitrogen (N) fertilizers such as urea, making their agricultural use challenging. Despite this, food waste‐derived soil amendments can enhance the physical and biological properties of soil, potentially creating synergistic effects when combined with synthetic N fertilizers. This study aimed to investigate effects of food waste‐derived amendments in soil applied at 50 kg ha−1 total N (compost, LD or SD) and synthetic N fertilizer [urea ammonium nitrate (UAN)] at 50 and 100 kg ha−1 total N. Over 56 days of soil incubation, greenhouse gases (CO2, N2O), soil chemistry (–N, –N, pH) and microbial biomass C (MBC) were measured. Results showed that LD + UAN 50 reduced cumulative N2O emissions by 23% compared with UAN 100, despite having the same total N and similar available N rate applied to soil. Replacing UAN with LD in farming practices can supply equivalent available N while lowering N2O emissions, offering a sustainable nutrient strategy. Moreover, applying food waste‐derived soil amendments can enhance N retention in soils, reducing the need for increased applications of synthetic N fertilizers to compensate for N deficits in farming. Food waste‐derived soil amendments can also act as a slower N release compared with UAN, reducing nitrogen run‐off. SD had the highest CO2 emissions, followed by LD and compost. SD + UAN 50 increased MBC levels because of higher carbon content and labile carbon, and available N because of the application of UAN. The major drawback of using SD compared with LD is that the process of evaporating LD to form SD causes high ammonia volatilization (ammonium in solution into ammonia gas) rates, reducing the available N in SD. Therefore, future studies should explore strategies to reduce ammonia volatilization of LD.

Nitrogen fertilizer replacement value of stockpiled and rotted dairy cattle manures for corn (Zea mays L.) from a long-term study

Context or problemAnimal manure is an excellent renewable source of plant nutrients, but the correct quantification of nutrient equivalents is affected by manure type and application rate as well as weather conditions that impact crop yields Objective or research questionThe objectives from a 32-year field experiment were to (1) compare the effects of mineral N fertilization and solid dairy cattle manure on corn grain yield; (2) determine the manure N fertilizer replacement value (NFRV), and (3) quantify environmental factors, mainly the impact of total precipitation during the critical period (silking) on corn yield and manure NFRV. MethodsA field experiment under continuous corn with annual manure application was conducted over 32 years in Ottawa, Ontario, Canada. Corn yield data were categorized into low, intermediate, and high N response groups. ResultsOn an equivalent amount of manure organic N basis, NFRVs were, on average, 0.38 (±0.02) for stockpiled manure (SM) and 0.27 (±0.02) for incompletely composted or rotted manure (RM), with a wide range of 0.12 (±0.02), 0.28 (±0.02), and 0.37 (±0.04) for RM, and 0.16 (±0.04), 0.39 (±0.03), and 0.48 (±0.04) for SM under the low, intermediate, and high N response conditions, respectively. Supplementing 100 kg synthetic fertilizer N ha−1 in low RM (50 Mg ha−1 fresh weight; f.w.), and 50 kg fertilizer N ha−1 in high RM (100 Mg ha−1 f.w.) application rates decreased NFRVs under low and intermediate N response conditions, whereas the addition of similar synthetic N in the corresponding SM rates reduced NFRVs only under low N response conditions. ConclusionsBased on the 32-year long-term study, we documented that the maximum economic synthetic N fertilizer rates for continuous corn cropping varied from 117 to 179 kg N ha−1 under the low N response, from 127 to 283 kg N ha−1 under the intermediate N response, and from 227 to 289 kg N ha−1 under the high N response conditions. The NFRVs of solid cattle manures varied according to corn yield-N response levels. Implications or significanceOur findings showed that the response of corn yields to manure NFRV depends on the level of yield-N response and climatic conditions. It also indicated the importance of soil organic amendments for improving the climate resilience of corn production, while simultaneously meeting the demand for more sustainable nutrient management of soil resources.

Assessment of Integrated Poultry Manure and Synthetic Fertilizer Effects on Maize (Zea mays) Growth and Soil Properties: A Study from Bayero University, Kano

The study investigated the effects of organic and inorganic nutrients on crop productivity and soil health, with a focus on maize growth and soil properties. It was conducted at Bayero University, Kano and comprised six treatments laid out in a Completely Randomized Design (CRD) with three replications. The treatments included poultry manure, synthetic fertilizers, and their combination. The research aimed to assess the impact of these treatments on maize growth and their residual effects on soil physical and chemical properties. Various plant growth parameters and soil properties were evaluated, and the data obtained were analyzed using Analysis of Variance (ANOVA) and Student-Newman-Keuls test (SNK). The results indicated that all treatments significantly influenced morphological parameters, including plant height, number of leaves, stem girth, and leaf area, compared to the control. Maize growth was notably higher with the application of integrated poultry and inorganic fertilizer or solely inorganic fertilizers. Additionally, soil organic carbon, total nitrogen, phosphorus, and potassium contents increased when poultry manure was applied alone or in combination with inorganic fertilizer. The application of poultry manure significantly raised soil pH, organic carbon content, total nitrogen, available phosphorus, exchangeable potassium, calcium, magnesium, and effective cation exchange capacity (ECEC) of the soil. Furthermore, the exchangeable acidity of the soil was reduced by the application of poultry manure alone. Soil texture was improved, soil bulk density decreased, and porosity increased due to the application of poultry manure. The study concluded that the combined application of poultry manure and inorganic fertilizer enhanced the growth of maize and could serve as a good soil management practice for tropical soils. It also suggested that integrating inorganic fertilizers with organic manures at optimum rates could improve crop productivity on a sustainable basis. The findings of this study may contribute to the development of sustainable nutrient management programs aimed at enhancing crop productivity with high efficiency and minimal nutrient loss in the future.

An in vitro evaluation of partial energy replacement in a total mixed ration with volatile fatty acids derived from agro-industrial residues

AbstractThe scientific interest in volatile fatty acids (VFAs) as an energy source and chemical precursor in ruminant diets has been longstanding, as it has significant implications for animal physiology and well-being. The present study explores the substitution of volatile fatty acids (VFAs) derived from agro-food residues via acidogenic fermentation as an alternative energy source in ruminant feed. Utilizing the gas production method, rumen digestibility assays were conducted, wherein the recovered VFA effluent from the acidogenic fermentation of apple pomace and potato protein liquor was substituted for 10%, 20%, and 30% of the total mixed ration (TMR) energy. Various parameters such as gas, VFA yield and composition, VFA peak intervals, changes in pH, and ammonium nitrogen content were investigated. Based on the results obtained, provision of 20% and 30% of the energy with VFAs did not increase methane production or did not cause significant pH alternations. Nevertheless, such supplementation resulted in increased production and accumulation of VFAs in the rumen media. The bioconversion of agro-food side streams into VFAs opens a new path in sustainable nutrient recovery and feed production from low value agro-industrial residues. Graphical Abstract