High Fertilizer Application Rates Research Articles

Application of nitrogen, phosphorus, potassium + carbon fertilizer improves the growth of Tecoma stans and the performance of its root-feeding biological control agent, Heikertingerella sp.

ABSTRACT The invasive tree Tecoma stans (L.) Juss. ex Kunth var stans (Bignoniaceae) has been targeted for biological control in South Africa since 2003. Plant nutrients contained in fertilizers typically improve host-plant quality, thereby enhancing the fitness of insect herbivores deployed as weed biocontrol agents. We investigated the effect of increasing nutrient levels (fertilizer treatments) on the growth of potted T. stans plants and on the subsequent performance of the root-feeding beetle Heikertingerella sp. (Chrysomelidae). Enhanced performance of Heikertingerella sp. in culture will improve mass-rearing initiatives for releases in South Africa. Ten newly emerged mating pairs of Heikertingerella sp. were exposed under glasshouse conditions to caged plants that were treated with four regimes of nitrogen: phosphorus: potassium 2:3:2 (14%) + carbon (8%) fertilizer, namely zero (control), low (5.6 g/m2), medium (9.4 g/m2) and high (13.2 g/m2). Increasing nutrient levels significantly increased leaf production and above – and below-ground biomass accumulation in T. stans plants. Similarly, the performance of Heikertingerella sp. was improved substantially, with significantly and progressively higher levels of P1 adult feeding and F1 progeny production, and significantly and progressively reduced F1 developmental times, under increasing nutrient levels. While F1 adult size was significantly increased by fertilizer application relative to the controls, there were no significant differences between the three nutrient levels. Although the high fertilizer application rates were the most suitable for the culturing and mass-rearing of Heikertingerella sp. adults, medium fertilizer applications may prove more economical to improve host-plant quality and boost beetle numbers for release.

Mitigation of soil nitrous oxide emissions during maize production with basalt amendments

Nitrous oxide (N2O) is a potent and long-lived greenhouse gas that accounts for roughly 6% of global anthropogenic greenhouse gas emissions, and it has risen from its preindustrial concentration of 270 ppb N2O to 332 ppb N2O as a result of human activities. The majority of anthropogenic N2O emissions (52–80%) come from agricultural settings due to high rates of reactive nitrogen fertilizer application. Amending soils with fine-grained basalt is gaining traction as a carbon dioxide removal (CDR) pathway, and model simulations suggest that this process may also significantly decrease soil N2O emissions. Here, we continuously measure N2O fluxes from large-scale maize mesocosms in a greenhouse setting and use a machine learning framework to assess the relative importance of the levers on N2O fluxes. We observe significant decreases in cumulative N2O emissions (between 29–32%) from mesocosm systems with basalt addition. We find that basalt application rate, soil pH, and surface soil moisture are the strongest levers on N2O emissions depending on the system settings. These results provide empirical support for a potentially significant co-benefit of deploying enhanced rock weathering of silicates (ERW) on managed lands, particularly those subject to elevated rates of reactive nitrogen input.

The Impact of Heavy Rainfall Variability on Fertilizer Application Rates: Evidence from Maize Farmers in China

Global warming increases the intensity and frequency of extreme weather events, which is harmful to agricultural production. Given that the overuse of fertilizer has been found to be a significant contributor to global warming, it is crucial to analyze the factors affecting farmers' fertilizer use and find appropriate fertilizer reduction measures. Agriculture is inherently risky, but previous studies have ignored the risk factors related to heavy rainfall variability, including fertilizer losses and the possible yield risks, which may lead to income risk. Using the 1995-2018 National Rural Fixed Observation Point Survey Data, this study examines the impact of heavy rainfall variability on maize farmers' fertilizer application rates, aiming to understand farmers' fertilization behavior in response to weather shocks. The results show that heavy rainfall variability significantly increases farmers' fertilizer application rates on maize. Furthermore, we find that heavy rainfall variability has greater effects on fertilizer use in hills and mountainous areas and areas with good irrigation conditions or high economic levels. When examining the potential channels underlying the estimated effects, we find that yield fluctuations are a channel through which heavy rainfall variability affects farmers' fertilizer use on maize. The above results indicate that farmers view applying extra fertilizer as a risk reducing activity in response to rainfall shocks, which helps to prevent low yield and income. Strengthening agricultural infrastructure construction according to local conditions and promoting fertilizer reduction technologies and products to reduce yield risk caused by heavy rainfall can help alleviate the problem of high fertilizer application rates by Chinese farmers.

Spatiotemporal Dynamics of Carbon Footprint of Main Crop Production in China.

As a major agricultural country, the comprehensive accounting of the dynamics and composition of the carbon footprint of major crops in China will provide a decision-making basis for environmental management and agricultural green development in the whole process of the major crop production system in China. To investigate the spatiotemporal dynamics of the carbon footprint for major crops in China, a life cycle-based carbon footprint approach was used to evaluate the carbon footprint per unit area (CFA) and per unit yield (CFY) of eight crops for the period of 1990 to 2019. Our results showed that the CFA for all major crops showed an increasing trend with time before 2016 but slowly decreased afterward, while the CFY decreased by 16-43% over the past 30 years due to the increase in crop yield. The three main grain crops, rice (4871 ± 418 kg CO2-eq · ha-1), wheat (2766 ± 552 kg CO2-eq · ha-1), and maize (2439 ± 530 kg CO2-eq · ha-1), showed the highest carbon footprint and contribution to the total greenhouse gas (GHG) emissions, mainly due to their larger cultivated areas and higher fertilizer application rates. CH4 emission was the major component of the carbon footprint for rice production, accounting for 66% and 48% of the CFA and CFY, respectively, while fertilizer production and usage were the largest components of carbon footprint for dryland crops, making up to 26-49% of the CFA and 26-50% of the CFY for different crops. The present study also highlighted the spatial and temporal patterns of the carbon footprint for major crops in China, which could serve as references for the development of best management practices for different crop production in China, to mitigate agricultural GHG emission and to pursue low-carbon agriculture.

Arsenic and Cadmium Accumulation in Soil as Affected by Continuous Organic Fertilizer Application: Implications for Clean Production

As and Cd in soil can be assimilated and accumulated by vegetables and can be subsequently ingested by humans. Contradictory effects of organic fertilizer application on As and Cd accumulation in soil have been reported in previous studies. An eight-year greenhouse study was conducted on a sandy loam soil in Beijing, China to investigate the effects of organic fertilizer application rate on soil properties, and As and Cd accumulation in soil. The contamination risk of pak choi grown after eight years’ application of organic fertilizer was also evaluated. Soil organic carbon increased 3.0–3.8 times with low, medium and high rates of fertilizer application in 2018 compared to the initial soil. Organic fertilizer application significantly increased soil nutrients and microbial biomass while it mildly affected soil pH. The bioavailability of As/Cd has decreased after eight years’ application of organic fertilizer. Pak choi crop harvested from all three treatments in 2018 did not pose a threat to human health, even for life-time consumption. Soil total As content significantly decreased with organic fertilizer application, mainly due to the lower As content in the applied fertilizer than that in soil. Continuous application of clean organic fertilizer can be adopted to reduce the contamination risk of highly contaminated soil in the soil–plant system.

Environmental Impact of Potentially Toxic Elements on Tropical Soils Used for Large-Scale Crop Commodities in the Eastern Amazon, Brazil

The Amazon soils demand high rates of fertilizer application to express high agricultural potential, making it necessary to carry out frequent monitoring of ecological functions and biogeochemical processes in this important biome. The concentrations of As, Ba, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn and contamination indexes were studied in Oxisol and Ultisols cultivated with citrus (Citrus sinensis (L.) Osbeck), oil palm (Elaeis guineensis Jacq.) and black pepper (Piper nigrum L.), at 26, 10 and 5 years of implantation, respectively. The potential risk of contamination was estimated by the enrichment (EF) and bioaccumulation (BAF) factors. Moderate enrichment of Ba, Pb and Zn (2 < EF < 5) and significant enrichment of As and Cu (5 < EF < 20) were observed. In addition, the following orders of bioaccumulation were found: oil palm—Cu > Zn > Hg > Ni > Ba > Co > As > Cr > Cd ≈ Pb; black pepper—Zn > Hg > Cu > Ba > Ni > Co > Pb >> As > Cr > Cd; and citrus—Hg > Ni > Ba > Zn > Co > Cu > As > Pb >> Cr > Cd. However, all elements are in concentrations below the prevention and investigation values established by Brazilian legislation, that is, the management practices in the crops studied are not contributing with damage to soil and human health risks.

Combinations of in-field moisture conservation and soil fertility management reduce effect of intra-seasonal dry spells on maize under semi-arid conditions

• Combining CT and mulching significantly increased soil water retention. • Maize yield was best under a combination of CT, mulching and mineral fertilizer + manure during a low rainfall season. • Under high rainfall, combining RT, mulching and mineral NPK fertilizer + manure gave the best maize yield on sandy soil. • On clay, maize yield was highest under CT, mulching and mineral NPK fertilizer + manure during both low and high rainfall. The high frequency of prolonged intra-season dry spells since the turn of the 21st century continues to heighten risk of crop failure in rainfed cropping systems of Southern Africa including Zimbabwe. This study explored the effects of combining in-field moisture conservation techniques and soil fertility management on maize ( Zea mays L.) productivity under rainfed conditions in semi-arid eastern Zimbabwe. Treatment combinations were co-designed with farmers through participatory approaches, and tested on-farm on sandy and clayey soils over three consecutive seasons (2015/16–2017/18). Two tillage practices namely conventional (CT) and reduced tillage (RT), with 30 % mulch cover of dried thatching grass ( Hyparrhenia filipendula (L.) Stapf) applied either at planting or tasseling or at both stages, were combined with low (35 kg N ha −1 , 14 kg P ha −1 and 3 t ha −1 of manure) and high (90 kg N ha −1 , 26 kg P ha −1 and 7 t ha −1 of manure) fertilizer application rates in a split-split plot design. Intra-seasonal dry spells were more frequent during the first two seasons (i.e. 2015/16 and 2016/17), while the 2017/18 season was rather wet with well-distributed rains. Soil water content varied significantly (p < 0.05) across treatments when a dry spell length was between 3 and 15 days, and 3 and 20 days on sandy and clayey soil, respectively. Conventional tillage retained 9–27% more soil water compared to RT, particularly when combined with mulching. During 2015/16 and 2016/17, seedling emergence occurred earlier by 2 days when mulching was applied at planting, while anthesis-silking interval (ASI) was shorter by 4 days following mulching at tasseling. On the sandy soil, the combination of CT + mulching (at both stages) + high fertilizer rate achieved the highest maize grain yield of 2.6 and 2.8 t ha -1 during the 2015/16 and 2016/17, respectively. However, during the wet 2017/18 season, the combination of RT + mulching at planting + high fertilizer rate yielded the best (3.5 t ha -1 ). On clayey soil, CT + mulching (at both stages) + high fertilizer rate gave the highest yields of 2.4, 2.9 and 3.4 t ha -1 in 2015/16, 2016/17 and 2017/18, respectively. Water use efficiency (WUE) was greatest under CT + mulching (at both stages) + high fertilizer rate especially during seasons that had high occurrence of intra-seasonal dry spells. Overall, the combination CT + mulching (at both stages) + high fertilizer rate increased maize yield by over 200 % and 300 % compared to the non-mulched treatments on sandy and clay soil, respectively, particularly during seasons with high incidences of intra-seasonal dry spells. Consequently, the treatment combination achieved the best economic returns during the drier seasons although income returns were reduced during the wetter season because of considerable yield loss due to waterlogging, particularly on the sandy soil. We thus conclude that mulching at strategic crop growth stages in combination with tillage and judicious addition of organic and inorganic fertilizers is a promising agronomic technique for reducing effects of intra-seasonal dry spells on maize productivity in rainfed smallholder cropping systems. Increasing farmer access to organic and inorganic fertilizers is, however, key to accelerated adoption of such agronomic techniques.

Nitrogen and phosphorus losses by surface runoff and soil microbial communities in a paddy field with different irrigation and fertilization managements.

Rice cultivation usually involves high water and fertilizer application rates leading to the nonpoint pollution of surface waters with phosphorus (P) and nitrogen (N). Here, a 10-year field experiment was conducted to investigate N and P losses and their impact factors under different irrigation and fertilization regimes. Results indicated that T2 (Chemical fertilizer of 240 kg N ha-1, 52 kg P ha-1, and 198 kg K ha-1 combined with shallow intermittent irrigation) decreased N loss by 48.9% compared with T1 (Chemical fertilizer of 273 kg N ha-1, 59 kg P ha-1, and 112 kg K ha-1 combined with traditional flooding irrigation). The loss ratio (total N loss loading/amount of applied N) of N was 9.24-15.90%, whereas that of P was 1.13-1.31% in all treatments. Nitrate N (NO3--N) loss was the major proportion accounting for 88.30-90.65% of dissolved inorganic N loss through surface runoff. Moreover, the N runoff loss was mainly due to high fertilizer input, soil NO3--N, and ammonium N (NH4+-N) contents. In addition, the N loss was accelerated by Bacteroidetes, Proteobacteria, Planotomycetes, Nitrospirae, Firmicutes bacteria and Ascomycota fungi, but decreased by Chytridiomycota fungi whose contribution to the N transformation process. Furthermore, T2 increased agronomic N use efficiency (AEN) and rice yield by 32.81% and 7.36%, respectively, in comparison with T1. These findings demonstrated that T2 might be an effective approach to ameliorate soil chemical properties, regulate microbial community structure, increase AEN and consequently reduce N losses as well as maintaining rice yields in the present study.

Characteristics and drivers of daily nitrogen and phosphorus losses from rice-rapeseed rotation systems in the middle reaches of the Yangtze River.

Crop production systems involving the use of high rates of fertilizer application caused significant losses of nitrogen (N) and phosphorus (P) to the environment, resulting in air pollution and water body eutrophication. Quantitating N and P losses and its drivers in crop production systems was critical for optimizing water and fertilizer management measures to mitigate the nutrient losses. However, N and P losses estimation remains highly uncertain in the field at event scale. We here quantify daily N and P losses and its drivers (daily N and P water input, N and P uptake, N and P water surplus, water loss, etc.) in rice-rapeseed growing systems by high-frequency field experiments at event scale in Central China. Results revealed that there were significant trade-off relationships between daily uptake and surplus for N and P during the whole growing stages both for rice and rapeseed. Although it was not significantly related in heading to mature stage for rapeseed, synergies between daily input or surplus and loss were found for N. Redundancy analysis revealed that water input and leaching loss contributed most for N and P loss in rice and rapeseed. The nutrient losses in easier stages should be reduced by postponing the base fertilizer and making it in line with the crop uptake. The study enhanced our knowledge of N and P losses mechanism for crop production systems and provided a scientific basis for optimization of water and fertilizer managements and N and P loss estimation models.

Changes in photosynthetic traits and their responses to increasing fertilization rates in soybean (Glycine max (L.) Merr.) during decades of genetic improvement

Changes in photosynthetic traits (PTs) during the long-term genetic improvement of soybean (Glycine max (L.) Merr.) yield have been studied, but detailed information on whether PT responses to environmental stress have improved, and their correlations with seed yield, are still unknown. Our objectives were to describe the changes in soybean PTs - leaf area index (LAI), leaf chlorophyll content (Chl), net photosynthetic rate (PN ), stomatal conductance (gs ), and transpiration rate (E) - during decades of genetic improvement, and to detect whether the responses to increasing fertilizer application rates (FRs) of the PTs of 13 different soybean cultivars released in various decades differed. All of the soybean PTs increased significantly along with the year in which each cultivar was released, under different FR treatments, indicating that PTs have improved during decades of genetic breeding. Medium FR (nitrogen) treatment (150 kg ha -1 ) increased PT values, to different extents, at all the investigated growth stages. Leaf area index, Chl, and PN of the old and middle cultivar groups at the full bloom (R2), full seed (R6), and beginning maturity (R7) stages decreased significantly under high FR treatment (300 kg ha-1 ) compared with the medium FR treatment. The former had no effect on any of the PTs of new cultivar group, or had promotive effects. Thus, the photosynthetic capacities of the new cultivars are more tolerant to high FR-related stress than older cultivars. The photosynthetic capacities, and tolerance to high FR-related stress, of soybean cultivars that were released in different years improved after long-term genetic breeding. © 2021 Society of Chemical Industry.

A comparison of the arbuscular mycorrhizal fungal communities among Bangladeshi modern high yielding and traditional rice varieties

Arbuscular Mycorrhizal Fungi (AMF) are ubiquitous soil microorganisms playing a vital role in the functioning of agricultural ecosystems. Although AMF are generally considered to have a low host specificity, it has been suggested that modern plant breeding has selected crop genotypes that are more selectively associated with AMF, possibly resulting in modern high yielding varieties (HYV) having a lower AMF diversity than traditional crop varieties. Whether this is true for paddy rice varieties under field conditions is not known so far. Here, we aimed at comparing differences of AMF communities among modern HYV and traditional rice varieties. We collected root and soil samples of five Bangladeshi rice varieties (two traditional and three modern HYV) from 40 different rice fields and quantified AMF richness, diversity and community composition through high throughput amplicon sequencing of the small subunit (SSU) of the ribosomal RNA cistron. Overall, 75 AMF OTUs, distributed over six AMF families with Glomeraceae as predominant family were found. After accounting for differences in soil conditions, we found that AMF diversity significantly differed among the five varieties and was higher in the traditional than modern varieties. The composition and structure of the AMF communities were distinct between the traditional and modern varieties. An indicator species analysis detected 9 OTUs significantly associated with traditional rice varieties, whereas no indicator OTUs were found for the modern HYV. We conclude that modern breeding coupled with high fertilizer application rates provide a plausible explanation for the reduced AMF diversity and the different AMF community composition between Bangladeshi modern HYV and traditional varieties.

Technological and institutional lock-in and excessive synthetic nitrogen fertilizer use on North American grain and oilseed farms

This intervention examines commodity grain and oilseed farmers’ over reliance on synthetic nitrogen fertilizer in North America. Most grain and oilseed farmers apply synthetic nitrogen fertilizer at rates higher than necessary in order to ensure maximum yields. At the same time, high fertilizer application rates lead to increased farm input expenses and generate significant amounts of water pollution and excessive greenhouse gas emissions. A number of low-cost alternative approaches have been developed which can significantly reduce or eliminate the need for synthetic nitrogen fertilizer while maintaining farm profitability. But such practices have only seen limited adoption by Canadian and US farmers. This is despite significant production cost savings and environmental benefits. A number technological and institutional factors work in combination to lock farmers into production models requiring large amounts of synthetic nitrogen fertilizer. They include crop varieties bred to thrive in artificially high nitrogen soil conditions, conventional tillage practices, restrictive financial arrangements, largely unenforced water quality laws, and non-diverse marketing outlets. These technological and institutional lock-ins are significant barriers to the adoption of alternative crop production practices that are less reliant upon synthetic nitrogen fertilizer.

Carbon footprint, non-renewable energy and land use of dual-purpose cattle systems in Colombia using a life cycle assessment approach

Dual-purpose cattle systems (DPS) include more than 75% of all dairy cows in Latin America and produce 40% of total milk production. Colombia has the fourth largest cattle herd in Latin America, and DPS account for 39% of the cattle population, and 58% of national milk production. Therefore, focusing on reducing the carbon footprint (CF) of DPS can have a huge contribution on mitigating the environmental impacts of the cattle farming sector. The present study aimed to estimate, based on a farm gate life cycle assessment (LCA) approach, the environmental impact of 1313 dual-purpose farms in Colombia. The study also aimed at identifying the main hotspots of negative environmental impacts and proposing possible mitigation options and their cost-effectiveness. The impact categories such as CF, non-renewable energy use, and land use were estimated using the 2019 Refinement to 2006 IPCC, databases, and locally estimated emission factors. Three methods of allocating environmental burdens to meat and milk products were applied. A principal component multivariate analysis (PCA) and a Hierarchical Clustering on Principal Components (HCPC) were performed. The largest source of greenhouse gas (GHG) in dual-purpose cattle systems comes directly from enteric fermentation, and manure deposited on pasture. The proportion of environmental burdens allocated to meat differed, with the economic method assigning the greater burden (36%), followed by energy content (30%) and mass production (13%). Four farms clusters and two production strategies were identified, a more intensive strategy with high proportion of improved pastures and higher fertilizer application rates (Clusters 1 and 2), and a more extensive with low input of fertilizers and grazing on natural pastures (Clusters 3 and 4). The CF values ranged between 2.1 and 4.2 CO2-eq per kg fat and protein corrected milk (FPCM) and between 9.0 and 18.3 CO2-eq per kg meat among clusters. CF, land use, and non-renewable energy use were lowest for clusters 1 and 3. Concerning cost-effectiveness, the adoption of improved pastures is a negative-cost measure and a promising climate change mitigation option. Overall, the CF could be reduced by around 25 to 48% for milk and meat. Therefore, our results suggest that it is possible to reduce GHG emissions by adopting improved pastures, better agricultural management practices, efficient fertilizer usage, and using the optimal stocking rate. It is expected that these reductions can be achieved with at negative costs.

Organic fertilizer application and Mg fertilizer promote banana yield and quality in an Udic Ferralsol.

Low soil fertility, high rates of fertilizer application and low yields and quality are major problems in intensive banana production in acid soils of south China. A field experiment was carried out for two years to determine the optimum management practices for maximizing soil health and banana yield and quality. The experiment consisted of an unamended control (CK) and lime (Lime), calcium magnesium phosphate fertilizer (CMP), organic fertilizer (OF), and organic fertilizer combined with calcium magnesium phosphate fertilizer (OFC) treatments. Soil nutrient concentrations and banana shoot biomass, nutrient uptake, yield and fruit quality were determined. Application of lime and CMP was found to increase soil pH and nutrient availability and increase banana yield. Yet, the banana biomass and yields in the Lime and CMP treatments were significantly lower than those in the OF and OFC treatments in which soil organic matter (SOM) content increased. Total soluble solids and soluble sugar contents increased in the CMP and organic fertilizer treatments. A consistent increase in Mg concentrations in banana leaves over the two years in the CMP and organic fertilizer treatments indicates that Mg is essential for banana production and quality. Short-term adding Mg from banana corms increased total soluble solids and soluble sugar content. The application of organic fertilizer combined with CMP or Mg solution is therefore recommended to increase soil health and promote the yield and quality of banana in intensively managed plantations in subtropical regions.

Estimation of greenhouse gas emissions in rice based cropping systems under fertigation using cool farm tool

Greenhouse gas emissions were estimated using the Cool Farm Tool (CFT) model in four rice based cropping systems under three fertigation regimes during the fifth year of a zero till system. Fertilizer N management strategies had a strong effect on N2O emissions, that were higher in rice-barley and ricechickpea cropping systems due to higher inherent available soil nitrogen. Rice-durum wheat, ricechickpea, rice-lentil and rice-barley cropping systems showed susceptibility in decreasing order for incremental fertilizer N application. The safe levels of fertilizer N application up to which the nitrous oxide emissions can be avoided are 17.60, 6.60, 13.46 and 5.31 kg ha−1 in these cropping systems respectively. Nitrous oxide emission intensity decreased with decrease in fertilizer and irrigation intensity and followed the order rice-chickpea> rice-lentil> rice-durum wheat> rice-barley. With similar flooding across treatments, methane emissions were statistically similar under various fertigation regimes and cropping systems. In kharif and rabi seasons respectively, CO2 emissions were attributable to fertilizer use and the amount of irrigation water applied, respectively and followed the order W3>W2>W1. Across cropping systems, CO2 emissions were more in rice-durum wheat attributable to fertilizer production and use. Cumulative GHG emissions (kg CO2-eq) were maximum in W3 followed by W2 and minimum in W1. During kharif season, maximum GHG emissions were estimated in rice-lentil cropping system. During rabi season, the emissions were higher in rice-durum wheat cropping system followed by rice barley, rice-lentil and rice chickpea cropping systems due to higher rates of fertilizer application in the respective cropping systems.

Effect of crop and grassland management on mycorrhizal fungi and soil aggregation

High rates of fertilizer application can disturb the Arbuscular mycorrhizal fungi (AMF) occurrence and life cycle in different tropical crop/ grassland systems compared to native vegetation. With the purpose of examine benefic AMF for crop production in experimental farms, the AMF community structure across different sites was studied. The native forest showed a greater diversity of AMF, followed by the grassland and cultivated crops. The number of AMF spores was greater in the natural site where ten genera of Glomeromycota, 14 species and four morphotypes were detected. The preserved native forest showed exclusive characteristics: higher amount of soil organic matter and higher macroaggregates and charcoal content than the samples of cultivated sites. This study showed variances in AMF communities as well as potential for AMF inoculant formulation.

A Model-Based Estimation of Resource Use Efficiencies in Maize Production in Nigeria

Food security is an increasingly serious problem worldwide, and especially in sub-Saharan Africa. As land and resources are limited and environmental problems caused by agriculture are worsening, more efficient ways to use the resources available must be found. The objective of this study was to display the spatial variability in crop yield and resource use efficiencies across Nigeria and to give recommendations for improvement. Based on simulations from the crop model LINTUL5 we analyzed the influence of fertilizer application on the parameters Water Use Efficiency (WUE), Fertilizer Use Efficiency (FUE), and Radiation Use Efficiency (RUE) in maize. High spatial variability was observed, especially between the north and the south of the country. The highest potential for yield improvement was found in the south. While WUE and RUE increased with higher rates of fertilizer application, FUE decreased with higher rates. In order to improve these resource use efficiencies, we suggest optimizing management strategies, demand-oriented fertilizer application, and breeding for efficient traits.

Integrated effect of fertilizer application and protective measures on weed infestation and potato yield

The results of the research have revealed integrated effect of the mineral fertilizer application and protective measures influence on weed infestation and potato yield. This effect was developed on the second half of the vegetation and expressed in more stronger inhibition of plant development (from 36,6 to 20,4 and 11,1 g/m2 on low, medium and high levels of mineral nutrition, respectively), in the reduction of species diversity (from 12 to 10 and 10 species/m2) and number of weeds (from 69 to 42 and 32 species/m2). The highest biological (biomass reduction – 95,3%, the number of weeds – 79%) and economic (yield increase – 228 с/ha or 107%) effect was achieved by the high rates of mineral fertilizer application and combined protective measures of potato crops from weeds. This variant was characterized by the greatest profitability (125,3%), whereas chemical protection providing double treatment of potato plantings with herbicides, even at the middle and high level of mineral nutrition, was less effective (102,6 and 109%) in economic terms.

N and P runoff losses in China's vegetable production systems: Loss characteristics, impact, and management practices

Vegetable production systems involve the use of high rates of fertilizer application, leading to significant losses of nitrogen (N) and phosphorus (P) to the environment, resulting in water body eutrophication through surface runoff and leaching. We here quantify, at the national level, total N and P runoff losses and the key factors controlling runoff in open-field vegetable systems in China, by summarizing data from 151 publications pertaining to 13 Chinese provinces using literature dating back to 1990. Rank analysis was employed to clarify the impact of N and P runoff losses in vegetable systems, and different strategies for controlling N and P entering into water bodies are being compared. Vegetable production systems have higher fertilizer inputs (264.3 kg N ha−1, 101.0 kg P ha−1) compared with upland crop and rice cultivation. As a result, annual total nitrogen (TN) and total phosphorus (TP) losses via runoff from vegetable systems reached 16.5 kg ha−1 and 3.45 kg ha−1, respectively, and the N and P loss ratio for fruit vegetable systems reached 13.1% and 3.95% of the total fertilizer input, respectively. In the summer-autumn growing season, soil nutrient losses were the highest, accounting for 44% to 89% of the whole year. Redundancy analysis revealed that the most critical factor determining runoff losses was runoff volume. N and P runoff losses were also largely dependent on total soil N (TSN) and Olsen-P, respectively. Therefore, quantitative data for the national N and P runoff losses in vegetable production systems provide a scientific basis for an effective optimization of fertilizer applications.

Forest residue removal decreases soil quality and affects wood productivity even with high rates of fertilizer application

Forest residues are frequently used as energy sources by Brazilian forest companies. The removal of such residues is known to reduce wood productivity, especially when fertilizer application rate is low. This study aimed to evaluate after two forest rotations the effects of forest residue management on wood productivity when fertilizer is applied at a high rate; and the effect of timber harvest intensity on soil organic matter and microbial activity. We assessed tree growth, soil microbial biomass and activity, and we fractionated soil organic matter (SOM) via its oxidation resistance. These assessments were performed after conducting a field trial comparing harvest residue management over two successive rotations in the same plots. We found no significant effect of treatments on wood productivity when the residues were removed for the first time; however, wood productivity reduced by 15% during the second rotation with residue removal even with high rates of fertilizer application. Further, 40% reduction in microbial biomass and soil respiration was noted with forest residue removal. At the reestablishment time, the SOM in the top soil (0–0.05 m layer) was 25% lower at the site where the forest residues were removed, and this difference increased to 50% at 300 days after the reestablishment. This reduction was found mainly in the SOM labile fraction.