Synthetic Fertilizer Treatment Research Articles

Linking the humification of organic amendments with size aggregate distribution: Insights into molecular composition using FT-ICR-MS

Soil organic matter (SOM) plays a pivotal role in enhancing physical and biological characteristics of soil. Humic substances constitute a substantial proportion of SOM and their increase can improve crop yields and promote agricultural sustainability. While previous research has primarily assessed the influence that humic acids (HAs) derived from natural water have on soil structure, our study focuses on the impact of HAs on soil aggregation under different fertilizer regimes. During the summer cropping season, maize was cultivated under organic and synthetic fertilizer treatments. The organic fertilizer treatment utilized barley (Hordeum vulgare L.) and hairy vetch (Vicia villosa R.) as an organic amendment five days prior to maize planting. The synthetic treatment included a synthetic fertilizer (NPK) applied at South Korea's recommended rates. The organic treatment resulted in significant improvements in the soil aggregates and stability (mean weight diameter, MWD; p < 0.05) compared to the synthetic fertilizer application. These improvements could be primarily attributed to the increased quantity and quality of HAs in the soil derived from the organic amendment. The amount of extracted HAs in the organic treatment was nearly twice that of the synthetic treatment. Additionally, the organic treatment had a 140 % larger MWD and a 40 % increase in total phenolic content compared to the synthetic treatment. The organic treatment also had an increased macronutrient uptake (p < 0.001), an 11 % increase in aboveground maize biomass, and a 21 % increase in grain yield relative to the synthetic treatment. Thus, the enhancement of HA properties through the incorporation of fresh organic manure can both directly and indirectly increase crop productivity.

Using bio-based fertilizer derived from peri‑urban wastes affects soil properties and lettuce yield and quality

The use of waste-derived fertilizers, also known as bio-based fertilizers (BBFs), for the production of ready-to-eat vegetables can efficiently contribute to sustainability and circularity. However, studies on the efficiency and safety of these fertilizers are needed. Thus, this study aimed to examine and characterize the effects of combined application of BBFs on lettuce yield and quality and soil properties in a trial conducted under open field conditions. The eight experimental treatments included green- or food waste compost combined with either human urine, food waste digestate or synthetic fertilizer and compared to treatments with synthetic fertilizer alone or in combination with manure. The control treatment received no BBF or other type of fertilizer. The results showed statistically similar fresh lettuce yields after 48 days among the treatments, all of which were larger than the yield of the unfertilized control treatment. The highest fresh yield (73 t ha−1) was observed with the combination of manure and synthetic fertilizer. Yield in treatments that received green waste or food waste composts tended to decrease slightly, more likely due to nitrogen immobilization after the application of incompletely stabilized composts and the low initial mineral N. Nitrate contents in fresh lettuce leaves were below the EU limits (3000 mg kg−1) in all the treatments. Analysis of pathogens and trace elements present in aboveground lettuce showed no significant risk. The application of BBFs also appeared to maintain the soil pH compared to synthetic fertilizer treatments. The important nutrient and carbon contents of BBFs and their positive effect on lettuce yield associated with their non-harmful impact on lettuce quality suggest that BBFs can be used for vegetable production and to increase the soil carbon stocks and contribute to city sustainability.

Fate of nitrogen and phosphorus from source-separated human urine in a calcareous soil

Human urine concentrates 88% of the nitrogen and 50% of the phosphorus excreted by humans, making it a potential alternative crop fertilizer. However, knowledge gaps remain on the fate of nitrogen in situations favouring NH3 volatilization and on the availability of P from urine in soils. This study aimed at identifying the fate of nitrogen and phosphorus supplied by human urine from source separation toilets in a calcareous soil. To this end, a spinach crop was fertilized with 2 different doses of human urine (170 kgN ha-1 + 8.5 kgP ha-1 and 510 kgN ha-1 + 25.5 kgP ha-1) and compared with a synthetic fertilizer treatment (170 kgN ha-1 + 8.5 kgP ha-1) and an unfertilized control. The experiment was conducted in 4 soil tanks (50-cm depth) in greenhouse conditions, according to a randomized block scheme. We monitored soil mineral nitrogen over time and simulated nitrogen volatilization using Hydrus-1D and Visual Minteq softwares. We also monitored soil phosphorus pools, carbon, nitrogen and phosphorus (CNP) in microbial biomass, soil pH and electrical conductivity. Only an excessive input of urine affected soil pH (decreasing it by 0.2 units) and soil conductivity (increasing it by 183%). The phosphorus supplied was either taken up by the crop or remained mostly in the available P pool, as demonstrated by a net increase of the resin and bicarbonate extractable P. Ammonium seemed to be nitrified within about 10days after application. However, both Visual Minteq and Hydrus models estimated that more than 50% of the nitrogen supplied was lost by ammonia volatilization. Overall, our results indicate that direct application of urine to a calcareous soil provides available nutrients for plant growth, but that heavy losses of volatilized nitrogen are to be expected. Our results also question whether long-term application could affect soil pH and salinity.

PhoD Harboring Microbial Community and Alkaline Phosphatase as Affected by Long Term Fertilization Regimes on a Calcareous Soil

Organic phosphorus (Po) may play a vital role in phosphorus availability via its mineralization by alkaline phosphatase (ALP), being encoded by phoD gene, in calcareous soil. Understanding the effects of long-term fertilization on the community of phoD harboring bacteria and the related alteration of the P availability owing to the changes in ALP secretion may offer a chance to elucidate the Po contribution to soil available P. Based on a long-term experiment, we analyzed the phoD gene harboring microbial diversity, abundance and composition, ALP and Po forms, and their relationship. The treatments involved were control without any fertilizers (CK), synthetic nitrogen and potassium (NK), synthetic nitrogen, phosphorus and potassium (NPK), NPK and crop stalk return (SNPK), and NPK plus organic manure (MNPK). Fertilization increased the abundance and diversity of phoD gene harboring microbial over CK. Those receiving NPK and NPK treatments integrated with organic supplements significantly improved the relative abundance of Proteobacteria but decreased Gemmatimonadetes at the phylum level, while all fertilized treatments appreciably increased the relative abundance of Lysobacter but decreased that of Gemmatirosa and Afipia, at the genus level. SNPK and MNPK treatments noticeably increased the relative abundance of Methylobacter but reduced Pseudomonas and Streptomyces relative to those receiving synthetic fertilizer treatments. Long-term fertilization markedly raised ALP activity, which was significantly and positively correlated with the relative abundance of the phylum Proteobacteria as represented by the genera Methylobacterium and Lysobacter. ALP was closely associated with moderately labile Po, followed by enzyme P, recalcitrant Po, and labile Po. The changes in phoD bacteria and ALP were mainly driven by soil organic carbon, Olsen P and pH. We concluded that the long-term fertilization, especially the addition of organic supplements, profoundly modified the soil properties and subsequently changed the diversity and relative abundance of phoD gene harboring bacteria, which promoted the activity of ALP, and thus the mineralization of various forms of Po (mainly moderately labile Po) to enhance the P availability.

Meta-Analysis of Yields of Crops Fertilized with Compost Tea and Anaerobic Digestate

Organic inputs constitute an alternative way to replace or reduce the use of agrochemicals in order to increase sustainability and reduce negative impacts of agriculture on the environment. A consistent determination of average yields obtained with organic fertilizers in comparison to synthetic fertilizers is necessary to assess their potential in both commercial and organic agriculture. To achieve this goal, a meta-analysis of existing scientific data of yields obtained with digestate or compost tea fertilization was performed. After a systematic bibliographic search of scientific publications, 35 final papers remained from &gt;1000 initial results. Data of crop yield with digestate or compost tea fertilization, as well as control and synthetic fertilizer treatments, were extracted from the selected articles and used to calculate response ratios (ratios of means), obtaining 106 observations. The meta-analysis showed that digestate fertilization produced yields 80% higher than the control. Yields were statistically similar to those obtained with conventional treatments with chemical fertilization (only 2% lower in average). The results for digestate are considered robust as the significance did not change after conducting publication bias analyses. However, the high heterogeneity observed suggests the existence of explanatory variables accounting for part of the observed dispersion. Subgroup analyses were conducted to determine the variation of the results of digestate across crop species and field or greenhouse experiments, while compost teas did not present adequate data quantity to obtain reliable results. According to this meta-analysis, anaerobic digestate had an acceptable performance as fertilizer for several crops at a reported application rate ranging from 100 to 480 kg N ha−1. Regarding compost tea, yields were 92% higher than the control and 10% lower than synthetic fertilization treatments, although more information is required to draw a conclusive result due to the low number of observations of this fertilizer. Further investigation is necessary to understand yield variations under different scenarios to study the influence of secondary variables and to propose management measures for producers.

Weed community dynamics under repeated fertilization with different nutrient sources over 5 years

Soil fertility management through the application of synthetic fertilizer or livestock manures is crucial to maintaining the productivity and profitability of cropping systems. Little, however, is known about the response of weed communities to different livestock manure nutrient sources. As weed communities with increased diversity are considered part of more sustainable agroecosystems, it is necessary to find management practices that result in diverse weed communities of acceptable densities without negative impacts on crop productivity. Here, we monitored the effect of five nutrient sources, with similar goals for nitrogen (N) management, including synthetic fertilizer, liquid pig manure, two types of solid pig manure, and solid dairy manure on the weed community in a five-year (2008-2012) study. The abundance, species richness, Simpson’s diversity, Simpson’s evenness, and species turnover in weed communities were assessed over time. Crop biomass, mid-season plant-accessible soil nitrate-N, and pre-season soil phosphorus were determined. The application of liquid pig manure or synthetic fertilizer enhanced crop biomass likely through increased crop accessibility to N. The continued use of these sources of nutrients over time, contributed to low density, low species richness, and low diversity weed communities, particularly through the decline of broadleaf weed species. Liquid pig manure and synthetic fertilizer treatments were lower in weed density and diversity than solid manures. Solid manure treatments were associated with increased weed densities and reduced crop biomass; however, these nutrient source treatments resulted in more diverse weed communities. Regardless of the nutrient treatments, we observed drastic declines in weed community abundance, species richness, and diversity in drier years. Our study suggests that a management practice that increases the accessibility of N to the crop, possibly through a mixture of solid manures and synthetic fertilizers or liquid pig manure, may be ideal for promoting a profitable cropping system with decreased densities and improved diversity in weed communities. Technological advances that provide more precise placement of solid manures to increase the accessibility of N to the crop, may further contribute to achieving such profitable and multifunctional agroecosystems.

The potential of soil amendment with insect exuviae and frass to control the cabbage root fly

AbstractReliable options to control the cabbage root fly, Delia radicum L., are lacking in many countries as restrictions on insecticide use have tightened due to environmental concerns. Although microbial control agents are often considered as a sustainable alternative, their application in agriculture is constrained by inconsistent efficacy owing to low field persistence. To stimulate naturally occurring beneficial microbes, soil amendment with the residual streams of insect production has been suggested as an alternative to synthetic fertilization and a new approach to microbial crop protection. In a set of greenhouse experiments, exuviae and frass of black soldier fly larvae, Hermetia illucens L., house crickets, Acheta domesticus L. and exuviae of mealworms, Tenebrio molitor L., were added to soil from an organically managed field. Exuviae and frass treatments were compared to treatments with synthetic fertilizer. Brussels sprouts, Brassica oleracea L., plants were grown in amended soil for 5 weeks before being infested with cabbage root fly larvae. Insect and plant performance were assessed by recording cabbage root fly survival, biomass and eclosion time and seed germination and plant biomass, respectively. Whereas soil amendment with black soldier fly frass or exuviae reduced cabbage root fly survival and biomass, respectively, amendment with house cricket or mealworm residual streams did not negatively affect root fly performance. Furthermore, seed germination was reduced in soil amended with house cricket exuviae, while amendment with either residual stream derived from black soldier fly larvae or house crickets resulted in lower plant shoot biomass compared with the synthetic fertilizer treatment. Amending soil with black soldier fly residual streams could become a novel and low‐cost tool to be integrated in cabbage root fly management programmes, especially where methods currently available are insufficient. Therefore, the mechanisms underlying the effects of insect‐derived soil amendments described here should be the focus of future research.

Partial substitution of manure reduces nitrous oxide emission with maintained yield in a winter wheat crop

Conventional fertilization of agricultural soils results in increased N2O emissions. As an alternative, the partial substitution of organic fertilizer may help to regulate N2O emissions. However, studies assessing the effects of partial substitution of organic fertilizer on both N2O emissions and yield stability are currently limited. We conducted a field experiment from 2017 to 2021 with six fertilizer regimes to examine the effects of partial substitution of manure on N2O emissions and yield stability. The tested fertilizer regimes, were CK (no fertilizer), CF (chemical fertilizer alone, N 300 kg ha−1, P2O5 150 kg ha−1, K2O 90 kg ha−1), CF + M (chemical fertilizer + organic manure), CFR (chemical fertilizer reduction, N 225 kg ha−1, P2O5 135 kg ha−1, K2O 75 kg ha−1), CFR + M (chemical fertilizer reduction + organic manure), and organic manure alone (M). Our results indicate that soil N2O emissions are primarily regulated by soil mineral N content in arid and semi-arid regions. Compared with CF, N2O emissions in the CF + M, CFR, CFR + M, and M treatments decreased by 16.8%, 23.9%, 42.0%, and 39.4%, respectively. The highest winter wheat yields were observed in CF, followed by CF + M, CFR, and CFR + M. However, the CFR + M treatment exhibited lower N2O emissions while maintaining high yield, compared with CF. Four consecutive years of yield data from 2017 to 2021 illustrated that a single application of organic fertilizer resulted in poor yield stability and that partial substitution of organic fertilizer resulted in the greatest yield stability. Overall, partial substitution of manure reduced N2O emissions while maintaining yield stability compared with the synthetic fertilizer treatment during the wheat growing season. Therefore, partial substitution of manure can be recommended as an optimal N fertilization regime for alleviating N2O emissions and contributing to food security in arid and semi-arid regions.

Effects of Fertilizers and Litter Treatment on Soil Nutrients in Korean Pine Plantation and its Natural Forest of Northeast China

Organic and inorganic soil fertilizer addition or removal pose significant effects on soil nutrients. As climate change and other anthropogenic factors are causing deprivation in soil nutrient profiles and altering its proper functioning, complete insight into fertilizer modification and its consequences is required for understanding the sustenance of forest ecosystems. In this regard, an experiment was conducted at Liangshui National Nature Reserve, northeast China, in which two forest soil types (i.e., Korean pine plantation and natural Korean pine forest) were evaluated for their response to external fertilizer applications and litter treatments. The litter treatments were litter application as Ck (undisturbed litter), RL (removed litter) and AL (Alter/double litter i.e., litter removed from RL was added in double litter plots), whereas the synthetic fertilizer treatments were Control (No added N and P), Low (5 g N m−2 a−1 + 5 g P m−2 a−1), Medium (15 g N m−2 a−1 + 10 g P m−2 a−1) and High (30 g N m−2 a−1 + 20 g P m−2 a−1). The outcome showed that soil organic carbon (SOC) was directly proportionate to forest litter amounts. Synthetic fertilizers affected soil total nitrogen (STN) and maximum amounts were recorded in plots with H: 30 g N m−2 a−1 + 20 g P m−2 a−1, as 3.03 ± 0.35 g kg−1 in AL. Similarly, altered litter/double was most effective in enhancing the quantity of soil total phosphorus (STP) (0.75 ± 0.04 g kg−1). Soil sampling carried out during the start and end of the experiment showed decreases in the sixth sampling of: SOC (4–23%), STN (7.5-10.8%) and STP (8.51–13.9%). A positive correlation was observed between SOC and total nitrogen; C:N ratio also increased with SOC. Principal component analysis (PCA) on captured a total of 62.1% variability, on the x-axis (35.1%) and on the y-axis (27%). It was concluded that combined application of N and P at the level of 30 g N m−2 a−1 + 20 g P m−2 a−1 under AL (Alter/double litter) treatment level improved soil total N and P content. The results clearly depicted that forest litter is an important source for building up of soil organic matter, however for attaining maximum sustenance capabilities in soil, the continuity of fertilizer application in either form is a prerequisite.

Effect of aqueous extract of clove basil (Ocimum gratissimum L.) and soil amendment with cassava peels compost on nutrients, pesticide residues, yield and antioxidant properties of sweet pepper (Capsicum annuum L.)

Natural agricultural inputs in sweet pepper cultivation can be beneficial for nutritional quality, and environmental and food safety. This research assessed the effect of the combined use of clove basil (Ocimum gratissimum) aqueous extract and cassava peel compost on the nutrients, pesticide residues, yield and antioxidant properties of sweet pepper fruits. The experiment was a split plot design of 04 blocks with 03 plots each and 03 repetitions, conducted in pots and in the field. The soil was amended with compost at 1kg/4kg and 2kg/3kg in pots, with 3kg/plot and 6kg/plot on field experiment, and 26.3 g of NPK (20.10.10) per plant was used as an inorganic amendment both in pots and field. Plants in both experiments were sprayed with clove basil extract, insecticide lambda-cyhalothrin or water. Sweet pepper fruits cultivated with composts and sprayed with clove basil extract exhibited the highest values of nutritional parameters, antioxidant properties and increased the yield by 93% in pots and 187% on field, as compared with synthetic fertilizer treatments. Organic fruits were free from pesticide residues and had the best values of Na/K and Ca/P ratios which are good indicators of their nutritional values. Sweet pepper plants sprayed with lambda-cyhalothrin or from farmers contained lambda-cyhalothrin at concentration of 0.0199 mg/kg. These results show that organic treatments improved the fruit nutrients, health-promoting properties and safety, and could be used to enhance the nutritional quality of sweet pepper while providing an efficient way of sustainable agriculture.

Mobilization of organic nitrogen and phosphorus and reduction of synthetic fertilizer usage by Ceriporia lacerata HG2011 in pepper cultivation

Overuse of synthetic fertilizers leads to soil deterioration, environmental pollution, and poor crop quality. To seek microbes that are effective in mobilizing nutrients accumulated in soils is of utmost significance to reduce fertilizer use and increase fertilizer efficiencies. Thus, the mobilization of organic nitrogen (N) and phosphorus (P) by a wood-rot fungus Ceriporia lacerata HG2011 and pepper performances in response to this fungus were investigated in the laboratory and field. The results showed that C. lacerata HG2011 grew well and produced extracellular protease and phosphatase to convert peptone into free amino acid and NH4+-N, and lecithin into soluble inorganic P in liquid culture. Similarly, NH4+-N, water soluble P and Olsen P were increased by the release of protease and phosphatase as the fungus grew on and in the sterile soil. Compared with only synthetic fertilizer treatment, pepper nutrient uptake (including N, P, and K), nutrient agronomic efficiency, and fruit yield and quality were improved by the application of synthetic fertilizers plus C. lacerata HG2011 and remained unchanged in the treatment of reduced synthetic fertilizers plus C. lacerata HG2011. The field soil that received this fungus showed the higher activities of protease and phosphatase, which lead to higher N and P availability than that without C. lacerata HG2011.Taken together, C. lacerata HG2011 mobilized organic nitrogen and phosphorus, increased pepper yield and quality, and reduced synthetic fertilizer use without yield and quality sacrifices, showing a promising new use in modern sustainable agriculture beyond medical, industrial, and environmental purposes.

Use of Recovered Struvite and Ammonium Nitrate in Fertigation in Tomato (Lycopersicum esculentum) Production for boosting Circular and Sustainable Horticulture

Struvite and ammonium nitrate are products obtained from widely studied processes to remove phosphorus (P) and nitrogen (N) from waste streams. To boost circularity in horticulture, these recovered products should be applied to edible crops. Particularly, struvite has not been implemented in fertigation as the unique source of P fertilizer. Therefore, a soilless system greenhouse experiment was conducted for tomato crops during two growing seasons. This study aims to compare the agronomic and environmental effectiveness of recovered products used in a nutrient solution for fertigation (NS) to synthetic fertilizer treatment. Moreover, two different N concentrations of the NS were tested to evaluate the impact on the N-leaching. Additionally, struvite dissolution tests were performed to ensure its solubility. Satisfactory results of struvite solubilization were obtained. Results show that both nutrient-recovered products can be used as fertilizers in NS, due to their non-statistical significance in total yield production and fruit quality. However, ammonium nitrate treatment, depending on the crop variety, showed a lower marketable yield. Moreover, the variation on N concentration input exhibited leachate concentration differences, with N leached percentage values from 36 to 13%. These results give deeper insights into the future potential utilization of nutrient-recovered products and technical data to optimize fertigation strategies.

Co-incorporation of manure and inorganic fertilizer improves leaf physiological traits, rice production and soil functionality in a paddy field

The combined use of organic manure and chemical fertilizer (CF) is considered to be a good method for sustaining high crop yields and improving soil quality. We performed a field experiment in 2019 at the research station of Guanxi University, to investigate the effects of cattle manure (CM) and poultry manure (PM) combined with CF on soil physical and biochemical properties, rice dry matter (DM) and nitrogen (N) accumulation and grain yield. We also evaluated differences in pre-and post-anthesis DM and N accumulation and their contributions to grain yield. The experiment consisted of six treatments: no N fertilizer (T1), 100% CF (T2), 60% CM + 40% CF (T3), 30% CM + 70% CF (T4), 60% PM + 40% CF (T5), and 30% PM + 70% CF (T6). All CF and organic manure treatments provided a total N of 150 kg ha−1. Results showed that the treatment T6 increased leaf net photosynthetic rate (Pn) by 11% and 13%, chlorophyll content by 13% and 15%, total biomass by 9% and 11% and grain yield by 11% and 17% in the early and late season, respectively, compared with T2. Similarly, the integrated manure and CF treatments improved post-antheis DM accumulation and soil properties, such as bulk density, organic carbon, total N, microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) relative to the CF-only treatments. Interestingly, increases in post-anthesis DM and N accumulation were further supported by enhanced leaf Pn and activity of N-metabolizing enzyme during the grain-filling period. Improvement in Pn and N-metabolizing enzyme activity were due to mainly improved soil quality in the combined manure and synthetic fertilizer treatments. Redundancy analysis (RDA) showed a strong relationship between grain yield and soil properties, and a stronger relationship was noted with soil MBC and MBN. Conclusively, a combination of 30% N from PM or CM with 70% N from CF is a promising option for improving soil quality and rice yield.

Response of Soil Bacterial Community Diversity and Composition to Time, Fertilization, and Plant Species in a Sub-Boreal Climate.

Pastures are an important part of crop and food systems in cold climates. Understanding how fertilization and plant species affect soil bacterial community diversity and composition is the key for understanding the role of soil bacteria in sustainable agriculture. To study the response of soil bacteria to different fertilization and cropping managements, a 3-year (2013–2015) field study was established. In the split-plot design, fertilizer treatment (unfertilized control, organic fertilizer, and synthetic fertilizer) was the main plot factor, and plant treatment [clear fallow, red clover (Trifolium pratense), timothy (Phleum pratense), and a mixture of red clover and timothy] was the sub-plot factor. Soil bacterial community diversity and composition, soil properties, and crop growth were investigated through two growing seasons in 2014 and 2015, with different nitrogen input levels. The community diversity measures (richness, Shannon diversity, and Shannon evenness) and composition changed over time (P < 0.05) and at different time scales. The community diversity was lower in 2014 than in 2015. The temporal differences were greater than the differences between treatments. The overall correlations of Shannon diversity to soil pH, NO, NH, and surplus nitrogen were positive and that of bacterial richness to crop dry matter yield was negative (P < 0.05). The major differences in diversity and community composition were found between fallow and planted treatments and between organic and synthetic fertilizer treatments. The differences between the planted plots were restricted to individual operational taxonomic units (OTUs). Soil moisture, total carbon content, and total nitrogen content correlated consistently with the community composition (P < 0.05). Compared to the unfertilized control, the nitrogen fertilizer loading enhanced the temporal change of community composition in pure timothy and in the mixture more than that in red clover, which further emphasizes the complexity of interactions between fertilization and cropping treatments on soil bacteria.

Evaluation of plant growth‐promoting rhizobacteria on stockpiled bermudagrass

AbstractA two‐year, small‐plot study was conducted to evaluate plant growth‐promoting rhizobacteria (PGPR) for biofertilization of fall‐stockpiled bermudagrass [Cynodon dactylon (L.) Pres.]. Eighteen, 10.8‐ft2 bermudagrass (cultivar ‘Coastal’) plots were mowed to 1‐inch stubble height prior to stockpiling. Experimental treatments included a negative control, synthetic fertilizer, PGPR single‐strain DH 44, DH 44 + fertilizer, PGPR multiple‐strain Blend 20, and Blend 20 + fertilizer (n = 3). Two PGPR applications were made, one at the beginning of each stockpiling season in mid‐August, and again 30 days later. Ammonium sulfate was applied at 50 lb N/acre concurrent with the first PGPR application. Each plot was divided into three subplots, which were harvested at different periods (i.e., mid‐November, mid‐December, and mid‐January) of each year to determine forage dry matter (DM) yield and nutritive value. Forage DM yield was greatest (P ≤ .03) for Blend 20 + fertilizer, but it was not different (P = .26) from that of the synthetic fertilizer treatment. Concentration of crude protein was least (P &lt; .04) for DH 44 and Blend 20 treatments. Concentrations of acid detergent fiber were not different among treatments, except for the negative control which was lower (P &lt; .05). In vitro true digestibility was not different (P &lt; .05) among treatments. These results indicate that PGPR may be a viable option for biofertilization; however, further investigation into the effect of PGPR inoculants at field level is needed.

Greenhouse Gas Emissions from an Irrigated Crop Rotation Utilizing Dairy Manure

Core Ideas Manure addition enhanced N2O losses. 0.13 to 0.24% of total N added was lost as N2O. Overall, global warming potential was lower in manure treatments than in fertilizer treatments. Information on greenhouse gas (GHG) emissions from manure application in cropping systems of the irrigated mountain west region is needed. The objectives of this study were to (i) determine the effect of manure application rate and frequency (annual vs. biennial) on GHG losses compared to synthetic fertilizer, (ii) determine the effect of irrigation on GHG losses and (iii) determine the overall global warming potential (GWP) of using manure vs. synthetic fertilizer. Treatments included dry manure rates of 18 or 52 Mg ha−1 applied annually or 36 Mg ha−1 applied biennially as well as synthetic fertilizer and control treatments. Cumulative losses of N2O‐N over the rotation ranged from 1.4 to 8.4 kg ha−1 with the 52 Mg ha−1 manure application losing the greatest amount of N2O‐N. Emission factors for the growing season indicated that 0.13 to 0.24% of total N applied was lost as N2O‐N. Cumulative CO2–C losses were greatest in the manure treatments, with approximately 7% of carbon added lost as CO2–C. Maximum N2O‐N fluxes occurred at soil moisture contents of 0.3 to 0.4 m3 m−3 and temperature near 25°C, while CO2–C emissions occurred over broader soil moisture and temperature conditions. The overall GWP associated with manure application indicated a net negative GWP for manure treatments while the synthetic fertilizer treatment was near neutral. Including manure in cropping system rotations can lead to enhanced GHG emission, however the benefits of enhanced SOC can outweigh these losses leading to lower GWP than use of synthetic fertilizer alone.

Poultry Litter Band Placement in No‐Till Cotton Affects Soil Nutrient Accumulation and Conservation

Core Ideas Applying poultry litter in bands below the soil surface leads to greater conservation of most litter‐derived nutrients. Fertilizing cotton with poultry litter, despite supplying additional Mn, leads to reduced extractable soil Mn and tissue Mn levels. A yearly application of 6.1 Mg ha‐1 poultry litter for three consecutive years failed to increase soil total C and N. The effect of subsurface poultry litter band placement relative to the plant row on long‐term nutrient conservation has not been fully investigated. The objective of this study was to determine whether poultry litter band placement affects the accumulation and conservation of selected soil nutrients in a no‐till cotton (Gossypium hirsutum L.) cropping system. The treatments consisted of an average of 6.1 Mg ha‐1 litter applied in 1.02‐m‐spaced subsurface bands (wide, SSw), 0.30‐m‐spaced subsurface bands (narrow, SSn), or 0.30‐m‐spaced surface bands (narrow, SFn); an unfertilized control (UTC); and a soil test‐based synthetic fertilizer treatment (Std). The results showed, relative to the Std, poultry litter, regardless of the placement, resulted in accumulation of extractable soil P, K, Mg, and Zn but not total C or N. A key finding in this study is that litter, despite supplying a 3‐yr total of 10.2 kg ha‐1 Mn, reduced extractable soil Mn by an average of 20% and cotton tissue Mn by as much as 40% relative to the Std treatment. The accumulation of extractable soil P and K and to some extent Mg and Zn was greater when litter was applied by subsurface rather than surface banding. The difference between the SSw and SSn treatments in extractable nutrient conservation was not consistent. Overall, this study showed applying poultry litter in subsurface bands rather than surface bands leads to greater conservation of nutrients. Regardless of the band placement, poultry litter reduced tissue and extractable soil Mn which may be beneficial to cotton production in soils with marginally low pH.

Chemical composition of windblown dust emitted from agricultural soils amended with biosolids

Abstract Biosolids are frequently applied to agricultural lands in dry regions, but wind erosion of these lands might transport biosolids particulates offsite and impact environmental quality. Our objective was to measure concentrations of EPA-regulated metals as well as macronutrients and micronutrients in soil and windblown sediment from a biosolids field experiment. A wind tunnel was used to generate windblown sediment from experimental plots subject to traditional (disk) or conservation (undercutter) tillage and application of biosolids or synthetic fertilizer on two measurement dates during the summer fallow phase of a winter wheat-summer fallow (WW-SF) rotation at Lind, WA in 2015 and 2016. Application of biosolids or use of undercutter tillage resulted in higher concentrations of heavy metals in the soil. For example, zinc (Zn) concentration in soil was 14% higher for undercutter than disk tillage and 21% higher for biosolids than synthetic fertilizer on the first measurement date in 2015. Differences in metal concentrations between treatments, however, were not as evident in windblown sediment. Similar results were found for nutrient concentrations in soil, but concentrations in windblown sediment were at least 10% lower for biosolids than synthetic fertilizer and undercutter than disk tillage on at least one measurement date. Little difference was found in loss of heavy metals and nutrients in windblown sediment between biosolids and synthetic fertilizer treatments. Our results suggest similar loss of metals and other elements from agriculture land after application of biosolids and synthetic fertilizer. Biosolids, however, are beneficial for increasing C and N content in soil.

Wind erosion potential of a winter wheat–summer fallow rotation after land application of biosolids

Abstract Conservation tillage is a viable management strategy to control soil wind erosion, but other strategies such as land application of biosolids that enhance soil quality may also reduce wind erosion. No studies have determined the effects of biosolids on wind erosion. Wind erosion potential of a silt loam was assessed using a portable wind tunnel after applying synthetic and biosolids fertilizer to traditional (disk) and conservation (undercutter) tillage practices during the summer fallow phase of a winter wheat-summer fallow (WW-SF) rotation in 2015 and 2016 in east-central Washington. Soil loss ranged from 12 to 61% lower for undercutter than disk tillage, possibly due to retention of more biomass on the soil surface of the undercutter versus disk tillage treatment. In contrast, soil loss was similar to or lower for biosolids as compared with synthetic fertilizer treatment. Our results suggest that biosolids applications to agricultural lands will have minimal impact on wind erosion.

EFFICACY OF SEVERAL MULTIPLE LIQUID BIOFERTILIZERS ON THE GROWTH AND PRODUCTION OF SWEET CORN (Zea mays L. saccharata)

This study was aimed at assessing the efficacy of several multiple liquid biofertilizers found in the market on the growth and production of sweet corn. A factorial completely randomized design was used. The first factor was the type of multiple liquid biofertilizers (PHMC) consisting of three levels, namely PHMC 1, PHMC 2, and PHMC 3. The second factor was synthetic fertilizer rates consisting of five levels, namely 0, 25, 50, 75, and 100% of recommended rate (R). Results showed that the application of PHMC 3 combined with synthetic fertilizer treatments (05 R and 25% R) significantly increased stem diameter (8 WAP). Plants treated with PHMC 3 application were found to have significantly higher number of leaves than those treated with PHMC 2 application at 6 WAP. Plant height, number of leaves, and weight, length, and circumference of main cob of plants treated with 50%R synthetic fertilizer were higher than those of plants treated with 0%R and 25%R synthetic fertilizer. Meanwhile, plants treated with 75%R synthetic fertilizer were found to have better values for girth, leave width, flowering time, harvesting time, number of cobs, dry weight of shoots and roots, grain total soluble solids (TSS) content, and cobs weight than those of plants treated with 0, 25, and 50%R synthetic fertilizer. Key words: sweet corn, multiple liquid biofertilizers, TSS, synthetic fertilizer.