Effects Of Manure Application Research Articles

Cerium Oxide Salicylic Acid Nanoparticles’ (CeO2: SA-NPs) Foliar Application and In-Soil Animal Manure Use Influence the Growth and Physiological Responses of Aloe vera L.

Aloe vera is an economic crop due to the presence of a gel-like substance inside the leaves, which contains polysaccharides, vitamins, proteins, fats, and amino acids. There is an ongoing need for this plant and its products for diverse food and pharmaceutical industries. To meet good agricultural practices, we studied the effect of manure application (0%, 10%, and 20% of v/v of soil) and foliar application with distilled water, salicylic acid (SA, 13.8 mg L−1 equivalent to 100 µM), cerium oxide nanoparticles (CeO2-NPs, 50 mg L−1), and cerium oxide salicylic acid nanoparticles (CeO2: SA-NPs; 100 µM + 50 mg L−1) on the growth and physiological responses of Aloe vera, and a factorial experiment was arranged based on a completely randomized design with three replications at Azarbaijan Shahid Madani University, Iran. The results showed that foliar application of CeO2: SA-NPs with the soil-based application of 10% and 20% manure increased plant dry weight and aloin content. The highest harvest index, economic yield, shoots-to-roots ratio, gel dry weight, chlorophyll a and b content, phenolics content of gel, and leaf and gel flavonoids’ content, as well as potassium, magnesium, zinc, and iron content, were obtained by the CeO2: SA-NPs × 20% manure treatment combination. The 10% and 20% manure and foliar application with CeO2-NPs, SA, and CeO2: SA-NPs increased the phenolics content of leaves compared to the control. Manure application (20%) positively affected the plant’s phosphorus content. The results revealed that co-application of soil-based cow manure and foliar CeO2: SA-NPs stimulated the growth and physiological responses of Aloe vera, and the results would be helpful to the agricultural extension sections and pioneer farmers.

Reduction in net greenhouse gas emissions through a combination of pig manure and reduced inorganic fertilizer application in a double-rice cropping system: Three-year results

Manure amendment in croplands is common practice for soil carbon sequestration, and may also reduce greenhouse gas emissions. Few studies focus on the effects of manure application on the net greenhouse gas emissions (NGHGE, the global warming impacts of soil carbon sequestration and CH4 and N2O emissions) in double-rice cropping fields. Herein, a field experiment was conducted to analyze the effects of pig manure application in combination with reduced chemical fertilizers on the NGHGE, soil properties, and yields in a double-rice paddy field in 2012–2015. Four treatments were included: 0 N (no nitrogen fertilizer); 1/2 N (chemical nitrogen fertilizer reduced by 50%); N (100% chemical nitrogen fertilizer); and 1/2 N + PM (pig manure complemented with chemical fertilizer application). The average annual CH4 emissions for 1/2 N + PM were 53%, 50%, and 32% higher than those for 0 N, 1/2 N, and N treatments, respectively (p < 0.05). The soil organic carbon sequestration rates (SOCSR) for 1/2 N + PM were 224%, 208%, and 192% higher than those for 0 N, 1/2 N, and N treatments, respectively (p < 0.05). The average annual N2O emissions from 1/2 N + PM were 51% lower than those from the N treatment. Compared to 0 N, 1/2 N and N treatments, the average NGHGE for 1/2 N + PM decreased by 41%, 41%, and 52%, and the average greenhouse gas intensity (GHGI, the yield-scaled NGHGE) from 1/2 N + PM reduced by 67%, 52%, and 53%, respectively. The decreases in NGHGE and GHGI were predominantly due to increased SOCSR (contributions of 187–308% and 81–325%, respectively) in 1/2 N + PM. The average soil nitrate, microbial biomass carbon and nitrogen, soil organic carbon contents, and pH value for 1/2 N + PM treatment were higher than those for the 1/2 N and N treatments (p < 0.05). Compared to 0 N and 1/2 N treatments, 1/2 N + PM treatment significantly increased the average rice yield. However, no significant difference in average yield was observed between the 1/2 N + PM and N treatments. Gross margin analysis showed that the economic profit for 1/2 N + PM was higher than that for the other three treatments. Thus, the combined application of reduced chemical fertilizers and pig manure is an effective and economic way to neutralize greenhouse gas emissions and increase soil fertility in double-rice cropping systems.

Bioaccumulation of Manure-borne antibiotic resistance genes in carrot and its exposure assessment.

The effect of manure application on the distribution and accumulation of antibiotic resistance genes (ARGs) in tissue of root vegetables remains unclear, which poses a bottleneck in assessing the health risks from root vegetables due to application of manure. Towards this goal, experiments were conducted in pots to investigate the distribution and bioaccumulation of ARGs in carrot tissues due to application of pig manure. The 144 ARGs targeting nine types of antibiotics were quantified by high throughput qPCR in the soil and plant samples. The rhizosphere was a hot spot for ARGs enrichment in the manured soil. The abundance, diversity, and bioaccumulation factors of ARGs in the phyllosphere were significantly higher than those of carrot root skin and tuber. Manure application increased bioaccumulation of 12 ARGs and 2 MGEs in carrot tuber with 124 the highest factor. The application of manure increased transfer of 10 ARGs and 3 MGEs from carrot skin to inner tuber by factors of 0.1-11.8. The average gene copy number of ARGs of per gram carrot root was about 4.8×104 and 1.1×106 in the control and the manured treatment, respectively. Children and adults may co-ingest 2.7×107 and 3.2×107 of ARGs copies/d from carrots grown with pig manure, using estimated human intake values. However, peeling may reduce the intake of ARGs by 28-91% and of MGEs by 46-59%. In conclusion, the application of pig manure increased the accumulation of ARGs in the skin of carrots, whereas peeling was an effective strategy to reduce the risk.

The Effect of Manure Application on Arsenic Mobilization and Methylation in Different Paddy Soils.

Organic matter plays an important rolein controlling arsenic(As) release and transformation in soil, however, little is known about the effect of manure application on As behavior in soils with different As contents. In this study, waterlogged incubations using various As-contaminated paddy soils with manure amendment were conducted to investigate how manure application influence As mobilization and methylation in different paddy soils. The results indicated that manure application increased As release in paddy soils with high As (> 30mgkg-1) contents. Moreover, our findings also showed that manure application increased the relative abundance of arsM-harboring Euryacheota and Planctomycetes at the phylum level and arsM-harbouring Methanocellaceae, Anaerolinea and Bellinea at genus level, thereby promoting As methylation. These results provide important insights for the significant variation in As mobilization and methylation in paddy soils amended with manure. Moreover, our results suggest that serious consideration should be given to the manure application in As-contaminated paddy soil.

Improving Soil Quality and Potato Productivity with Manure and High-Residue Cover Crops in Eastern Canada.

Under intensive low residue agricultural systems, such as those involving potato (Solanum tuberosum L.)-based systems, stagnant crop yields and declining soil health and environmental quality are common issues. This study evaluated the effects of pen-pack cow (Bos Taurus) manure application (20 Mg·ha−1) and cover crops on nitrate dynamics and soil N supply capacity, subsequent potato yield, selected soil properties, and soil-borne disease. Eight cover crops were tested and included grasses, legumes, or a mixture of legumes and grasses, with red clover (Trifolium pratense L.) used as a control. Forage pearl millet (Pennisetum glaucum L.) was associated with highest dry matter. On average, red clover had 88% higher total N accumulation than the treatments mixing grasses and legumes, and the former was associated with higher soil nitrate in fall before residue incorporation and overwinter, but this was not translated into increased potato yields. Pearl millet and sorghum sudangrass (Sorghum bicolor × sorghum bicolor var. Sudanese) were associated with lower soil nitrate in comparison to red clover while being associated with higher total potato yield and lower numerical value of root-lesion nematodes (Pratylenchus penetrans), although this was not statistically significant at 5% probability level. Manure incorporation increased total and marketable yield by 28% and 26%, respectively, and increased soil N supply capacity by an average of 44%. Carbon dioxide released after a short incubation as a proxy of soil microbial respiration increased by an average of 27% with manure application. Our study quantified the positive effect of manure application and high-residue cover crops on soil quality and potato yield for the province of Prince Edward Island.

Effect of Manure Application on Net Nitrification Rates, Heavy Metal Concentrations and Nitrifying Archaea/Bacteria in Soils.

In this study, we determined the effect of manure application on net nitrification rates (NNRs), heavy metal concentrations (HMCs), and abundance of ammonia-oxidizing archaea (AOA)/bacteria (AOB), and nitrite-oxidizing bacteria (NOB) in soil. HMCs were measured by atomic absorption spectroscopy. Abundance of AOA, AOB, and NOB was enumerated by q-PCR. NNRs ranged from 2.8 to 14.7mgkg-1h-1 and were significantly (p < 0.05) increased in manure soils as compared to control soils. NNRs were affected by pH 7 and temperature 30°C. Cd, Fe and Pb concentrations were classified as excessively polluted, moderate contamination and slight pollution, respectively, in the manure soils. NNRs and concentrations of Fe and Pb were significantly (p < 0.00) positive correlated, but Cu and Cd were significantly (p < 0.00) negative correlated with NNRs. Application of manure significantly (p < 0.05) increased HMCs (Fe, Cu, and Pb), which have indirect and direct effects on NNRs and nitrifying bacteria.

Erythromycin Treatment of Brassica campestris Seedlings Impacts the Photosynthetic and Protein Synthesis Pathways.

Erythromycin (Ery) is a commonly used veterinary drug that prevents infections and promotes the growth of farm animals. Ery is often detected in agricultural fields due to the effects of manure application in the ecosystem. However, there is a lack of information on Ery toxicity in crops. In this study, we performed a comparative proteomic analysis to identify the molecular mechanisms of Ery toxicity during seedling growth based on our observation of a decrease in chlorophyll (Chl) contents using Brassica campestris. A total of 452 differentially abundant proteins (DAPs) were identified including a ribulose-1,5-bisphosphate carboxylase (RuBisCO). The proteomic analysis according to gene ontology (GO) classification revealed that many of these DAPs responding to Ery treatment functioned in a cellular process and a metabolic process. The molecular function analysis showed that DAPs classified within catalytic activity were predominantly changed by Ery, including metabolite interconversion enzyme and protein modifying enzyme. An analysis of functional pathways using MapMan revealed that many photosynthesis components were downregulated, whereas many protein biosynthesis components were upregulated. A good relationship was observed between protein and transcript abundance in a photosynthetic pathway, as determined by qPCR analysis. These combined results suggest that Ery affects plant physiological activity by downregulating protein abundance in the photosynthetic pathway.

Coexistence between antibiotic resistance genes and metal resistance genes in manure-fertilized soils

Antibiotics and metals introduced during manure application are believed to be the major drivers of the bloom and spread of antibiotic resistance genes (ARGs) and metal resistance genes (MRGs) in agricultural environments. However, the coexistence of multidrug resistance (MDR) and metal resistance and the effects of manure application on the coexistence are less studied. Here, we profiled the coexistence patterns of 9919 MDR genes (MDRGs) and 25,312 MRGs in paddy fields with manure or inorganic fertilization. The abundances of both MDRGs and MRGs were higher under manure fertilization than inorganic fertilization. Network analysis determined that coexistence between MDRGs and MRGs was much more frequent in manure-fertilized soils than in inorganic-fertilized soils. Manure application drove this coexistence by not only directly introducing resistance genes but also increasing co-selection through antibiotics and metals, and stimulating their potential common hosts, including species of Actinobacterium WWH12, Bacillus, Geobacter, Solirubrobacter, Acidobacteriales, Bacillales, Chloroflexi, Methyloligellaceae and Xanthobacteraceae. Soil antibiotic resistance was significantly predicted by the coexistence of major multidrug efflux genes (mfs, mex, abc, mate and smr) and MRGs. The coexistence between MDRGs and MRGs explained 18% of the increase in soil antibiotic resistance. Such coexistence is nonnegligible and permits the promotion of soil antibiotic resistance, thus posing a potential threat to both agroecosystems and humans.

Response of N2O emission to manure application in field trials of agricultural soils across the globe

The response of soil nitrous oxide (N2O) emission to manure application has been widely reported for laboratory experiments. However, the in-situ effects of manure application on soil N2O emission from field trials (i.e. real-world conditions) and related mechanisms are poorly understood at the global scale. Here, we performed a meta-analysis using 262 field observations from 44 publications to assess the in-situ effects of manure application on soil N2O emission and factors regulating N2O emission (e.g., agricultural practices, manure characteristics and initial soil properties). Our analysis found that manure application significantly increased soil N2O emission in field trials. The largest N2O emissions were observed in soils from warm temperate climates, planted with upland non-leguminous crops and using raw manure. Notably, water-filled pore space (WFPS) significantly affected N2O emission; soils with 50–90% WFPS had the highest N2O emissions. Initial soil properties (e.g. pH, texture and organic carbon (C)) were generally not significant for predicting N2O emission, possibly due to changes in soil properties induced by manure additions. Manures with carbon: nitrogen ratios (C:N) of 10–15 and C contents of 100–300 g C kg−1 produced the lowest N2O emission. The net N2O emission factor (1.13%) resulting from manure application was similar to additions of synthetic N fertilizer (1.25%) and crop residues (1.06%), suggesting that manure application resulted in a similar N2O emission to other soil amendments. Our analysis provides a scientific basis for manure management options to minimize N2O emissions from animal waste disposal on agricultural lands globally.

A multi-approach assessment of land use effects on groundwater quality in a karstic aquifer

Groundwater represents almost half of the drinking water worldwide and more than one third of water used for irrigation. Agro-industrial activities affect water resources in several manners; one of the most important is leaching of agrochemical residues. This research identifies the major contributors of changes in groundwater quality comparing two contrasting land uses in a karstic area of the Yucatan peninsula as case study. Using a multiple approach, we assess the impact of land use with physicochemical data, multivariate analyses, hydrogeochemistry and nitrate isotopic composition. We confirmed that agricultural land use has a greater impact on groundwater quality, observed in higher concentration of nitrates, ammonium, potassium and electrical conductivity. Seasonality has an influence on phosphates and the chemical composition of the groundwater, increasing the concentration of dissolved substances in the rainy season. There was a clear effect of manure application in the agricultural zone and the nitrate isotopic composition of groundwater points toward recharge in certain areas. We consider that seasonality and land use effects are intertwined and sometimes difficult to separate, likely because of land use intensity and hydrogeochemical process at a local scale. Finally, we observed poor groundwater quality in the agricultural area during the wet season; thus, it is desirable to maintain non-agricultural areas that provide groundwater of appropriate quality.

Effects of manure fertilizer on crop yield and soil properties in China: A meta-analysis

The intensive use of mineral fertilizer may have negative effects on plant growth and the soil environment, but the application of manure could alleviate these problems. However, the effects of manure application on crop yield and soil properties in different climates, soil conditions, and management practices should be investigated before we could conclude that it is universally practical. We performed a meta-analysis of 774 comparisons from 141 published studies and found that manure application increased yield by an average of 7.6% compared to mineral fertilizer. The effects of manure application were more pronounced in acidic soils, warm and/or humid climates, and longer experimental periods. Manure application also increased soil pH (3.3%), water-stable aggregation (28.8%), soil organic carbon (17.7%), total (15.5%) and available nitrogen (16.0%), available phosphorus (66.2%), available potassium (19.1%), the activities of urease (23.5%), sucrase (18.3%), and catalase (16.1%), and the abundances of bacteria (60.0%), fungi (27.7%), and actinomyces (38.0%). Manure application decreased soil bulk density (−3.9%). Increases in the nutrient pool and decompositional capacity of the soil may explain the positive effects of manure application on yield. Our results indicate that long-term manure application may improve sustainable soil productivity and crop yield in China.

Beneficial arthropods as potential biocontrol candidates of thrips (Thysanoptera: Thripidae) occurring in Tunisian citrus orchards

Thrips are major economic insect pests of citrus worldwide. During the few last years these insects have become serious pests of citrus in Tunisia. The objective of this study was to determine the species of thrips’ natural enemies occurring in citrus orchards and assess the effects of manure application on the abundance of soil predatory mites. Sampling of thrips and their natural enemies was performed in citrus orchards in northern Tunisia from 2015 to 2017. Results revealed that (i) the most abundant predatory species found on plant leaves was Chrysoperla carnea representing 40.38% of the total number of natural enemies collected, followed by Coccinella septempunctata (13.57%) and that (ii) the most abundant soil predatory mite was Parasitus americanus representing 43.44% of the total number of predatory mites collected, followed by Stratiolaelaps scimitus, Pachylaelaps imitans and Odontoscirus sp. (9.43%, 6.45% and 5.41%, respectively). Higher population densities of P. americanus and S. scimitus in the soil were directly correlated with decreased thrips’ abundance and reduced plant damage. Our findings suggest that manure application significantly affects the abundance of both predatory mites and thrips in the soil. Here we provide first knowledge on natural enemies’ action against thrips and their potential use as biocontrol agents in Tunisian citrus orchards. The implications of the obtained results for developing and implementing the most eco-friendly and sustainable pest management options for citrus pest thrips are stated and discussed herein.

Antibiotic resistance gene profile changes in cropland soil after manure application and rainfall.

Land application of manure introduces gastrointestinal microbes into the environment, including bacteria carrying antibiotic resistance genes (ARGs). Measuring soil ARGs is important for active stewardship efforts to minimize gene flow from agricultural production systems; however, the variety of sampling protocols and target genes makes it difficult to compare ARG results between studies. We used polymerase chain reaction (PCR) methods to characterize and/or quantify 27 ARG targets in soils from 20 replicate, long-term no-till plots, before and after swine manure application and simulated rainfall and runoff. All samples were negative for the 10 b-lactamase genes assayed. For tetracycline resistance, only source manure and post-application soil samples were positive. The mean number of macrolide, sulfonamide, and integrase genes increased in post-application soils when compared with source manure, but at plot level only, 1/20, 5/20, and 11/20 plots post-application showed an increase in erm(B), sulI, and intI1, respectively. Results confirmed the potential for temporary blooms of ARGs after manure application, likely linked to soil moisture levels. Results highlight uneven distribution of ARG targets, even within the same soil type and at the farm plot level. This heterogeneity presents a challenge for separating effects of manure application from background ARG noise under field conditions and needs to be considered when designing studies to evaluate the impact of best management practices to reduce ARG or for surveillance. We propose expressing normalized quantitative PCR (qPCR) ARG values as the number of ARG targets per 100,000 16S ribosomal RNA genes for ease of interpretation and to align with incidence rate data.

Effect of Sheep Manure and Its Produced Vermicompost and Biochar on the Properties of a Calcareous Soil after Barley Harvest

ABSTRACTConversion of manures to vermicompost and biochar may alleviate some negative effects of manure application to soil but the efficiency of the produced vermicompost and biochar as compared to their feedstocks is not well-known. In the current investigation, we compared the effects of sheep manure and its derived vermicompost and biochar (pyrolyzed at 400°C for 4 h) on the properties of a calcareous soil that planted with five cultivars of barley (Behrokh, Khatam, Reyhaneh03, Fajr 30 and Nimrooz) for 60 days. Different soil properties and availability of nutrients and barley yield were determined after plant harvest. The biochar significantly increased barley yield rather than control (4.20 vs. 3.57 g pot−1), but sheep manure and vermicompost had no effect on it (3.51 and 3.37 g pot−1, respectively). Fajr 30 and Nimrooz (3.52 and 3.42 g pot−1, respectively) had significantly lower yield than other cultivars. Biochar increased soil pH up to 8.2. Soil salinity was increased by application of all organic materials (increase to 16–36%). Cation exchange capacity (CEC) and organic matter content of soil were also increased by all organic materials application (0.4–0.9 cmol kg−1 and 0.33–0.50%, respectively). All organic materials increased total nitrogen (N), but this increase was the highest with sheep manure application (53%). The availability of phosphorus (P) and potassium (K) was increased significantly by application of all organic materials, and this increase was the highest with biochar application (19 and 309 mg kg−1, respectively). Biochar application had no effect on the availability of micronutrients, but application of sheep manure and vermicompost increased the availability of iron (Fe) (0.62 and 0.48 mg kg−1, respectively) and zinc (Zn) (0.18 and 0.37 mg kg−1, respectively). Generally, organic materials may change the status of soil nutrients via change in soil pH, organic matter content, release of nutrients, increase in soil CEC and formation of soluble complex with nutrients.

Influence of Applied Cattle Manure on Winter Wheat (Triticum aestivum L.) Grain Yield, Soil pH and Soil Organic Carbon

ABSTRACTAnimal manure is used in crop production to improve crop yield and soil properties. The impact of cattle manure applied in one year on yield and soil properties in the subsequent years has not been extensively studied. This work evaluated the effect of manure application on winter wheat grain yield (Triticum aestivum L.), soil organic carbon (SOC), and soil pH. Cattle manure was applied once every four years at a rate of 267 kg N ha−1. Grain yield and soil samples (0–15 cm) were collected annually from the Magruder Plots, Oklahoma. Soil samples were analyzed using a glass electrode (pH) and LECO dry combustion analyzer (SOC). The highest yield (2.8 Mg ha−1) occurred in the second year after manure application. Yield in the second year exceeded yield in the first year by 66%. Yields in the third and fourth year were similar to yields in the other years. No changes in soil pH and SOC were observed in each of the four years that constituted the manure application cycle. Cattle manure (267 kg N ha−1) could be applied once to serve a four-year period without major yield differences while also improving soil pH and SOC when compared to the check.

Ten-year application of cattle manure contributes to the build-up of soil organic matter in eroded Mollisols

Amendment of animal manures into eroded soils is an important approach to improving nutrient status and increasing the concentration of soil organic carbon (SOC). However, the contribution of the manure carbon to SOC and its variation along soil profile has not been quantified. We simulated soil erosion in a mollisol by removing the top soils of 0-, 5-, 10-, 20-, and 30-cm depth and compared SOC in soil profiles 10 years after either chemical fertilization alone or combined with cattle manure application. Increasing erosion depth decreased SOC concentration and weakened soil aggregation. Compared to the chemical fertilization only, the addition of cattle manure significantly increased SOC accumulation and soil aggregation, which mainly occurred in 0–40-cm depths. The greatest effect of manure application was observed in the 10-cm erosion treatment. The application of cattle manure increased the 13C abundance in aggregates and bulk soil in the top 40 cm of soil profile. Using the natural 13C abundance method, we quantified the contribution of the cattle manure to SOC at 0–40-cm depths ranging from 1.1 to 8.4% across erosion treatments. The greatest contribution of the manure-C to SOC occurred in surface layer with 10 cm of soil removal. The application of animal manures was recommended for restoring severely eroded soils.

Influence of Chicken Manure Amendment on the Thermal Properties of Selected Benchmark Soils in Zambia

Influence of Chicken Manure amendment on the thermal properties of selected Benchmark soils in Zambia was investigated in the laboratory under soil column experiments. Five benchmark soils were exerted to four chicken manure amendment rates of 0% (control), 2%, 4% and 6% on a weight basis. Soil temperature profiles were monitored in soil columns exerted to artificial heat source and generated data was used to compute the thermal properties of the soils. The effect of manure application on the soil thermal properties was strongly related to soil type and application rate. Significant differences (p < 0.05) were observed in volumetric heat capacity, thermal diffusivity and damping depth among the benchmark soils. The volumetric heat capacity varied from 3.87 MJ·m−3·c−1 (Mushemi series) to 8.62 MJ·m−3·c−1 (Makeni series) and attributed to differences in soil characteristics. Thermal diffusivity varied from 0.028 m2·s−1 (Makeni series) to 0.069 m2·s−1 (Mushemi series) a reverse trend to thermal conductivity. A similar trend was observed with damping depth however thermal conductivity was not significantly different among the benchmark soils. The studied soils showed significant differences (p < 0.05) in their thermal properties with chicken manure amendment. Thermal conductivity (λ), thermal diffusivity (Dh) and damping depth (d) decreased while volumetric heat capacity (Cv) increased with increased chicken manure addition. The differences in these thermal properties were attributed to differences in soil properties. These results suggest that chicken manure application can be an important intervention in regulation of the thermal properties of the soil and consequently the thermal regime of the soil.

Long‐Term Manure Application Effects on Nutrients and Selected Enzymes Involved in Their Cycling

Core Ideas We assessed long‐term manure rates and application times on soil nutrients and enzymes at two sites. Increasing manure rate enhanced soil fertility but hydrolase enzymes showed a quadratic trend. Manure application prior to period of heavy rainfall (spring and fall) was associated with phosphorus losses. Peroxidase and phenol oxidase activities declined with increasing manure application rates. Oxidative enzyme activities were good indices of long‐term soil organic carbon storage. We investigated how soil nutrients (soil organic carbon [SOC], nitrogen [N], and Mehlich‐3‐extractable phosphorus [P‐M3]) and enzymes involved in their cycling were impacted by 10 yr of beef cattle manure application at two sites in Nova Scotia, Canada: a dikeland site (silty clay loam) and an upland site (sandy loam site), under timothy (Phleum pratense L.) cover. Manure was applied at four rates (from 0 to 300 kg total N ha−1) at different times (spring, summer, early fall, and late fall). Activities of hydrolytic enzymes: β‐glucosidase (BG), cellobiohydrolase (CB), leucine aminopeptidase (LAP), and phosphomonoesterase (PME) and oxidative enzymes: phenol oxidase (PO), peroxidase (PP), were quantified. We hypothesize that manure application will increase soil nutrients and BG, CB, LAP, and PME activities and will decrease PO and PP activities. After 10 yr of manure application, compared to a control, soil pH, SOC, N, and P‐M3 increased linearly by 41, 45, and 125%, respectively, with increasing manure rate, while BG, CB, PME, and LAP activities showed a quadratic response. Conversely, enzymes degrading less labile components (PP and PO) declined with increasing manure rate. Higher SOC and P‐M3 contents and higher LAP activity were found at the upland site, whereas higher PME, PP, and PO activities were found at the dikeland site. Inverse relationships between PME activity and P‐M3 content and between PP activity and SOC or N content were found, whereas a positive correlation between N content and LAP activity was observed. Regular manure application is a good way to sustain soil fertility, with the extent of soil C storage controlled by soil type. The optimal rate and timing of manure application is essential, since application prior to periods of heavy rainfall is associated with phosphorus losses. Our results demonstrated that oxidative enzymes (PP and PO) are good indices of long‐term SOC storage. The lower their activity, the higher is the SOC sequestration.

Tillage Methods and Poultry Manure Application Effects on the Growth and Yield of Groundnut (Arachis hypogaea L.) in Calabar, Nigeria

Tillage Methods and Poultry Manure Application Effects on the Growth and Yield of Groundnut (Arachis hypogaea L.) in Calabar, Nigeria

Regional Variations of Bovine and Porcine Fecal Pollution as a Function of Landscape, Nutrient, and Hydrological Factors.

The effects of manure application in agriculture on surface water quality has become a local to global problem because of the adverse consequences on public health and food security. This study evaluated (i) the spatial distribution of bovine (cow) and porcine (pig) genetic fecal markers, (ii) how hydrologic factors influenced these genetic markers, and (iii) their variations as a function of land use, nutrients, and other physiochemical factors. We collected 189 samples from 63 watersheds in Michigan's Lower Peninsula during baseflow, spring melt, and summer rain conditions. For each sample, we quantified the concentrations of bovine and porcine genetic markers by digital droplet polymerase chain reaction and measured , dissolved oxygen, pH, temperature, total phosphorus, total nitrogen, nitrate-nitrite (NO), ammonia (NH), soluble reactive phosphorus, streamflow, and watershed specific precipitation. Bovine and porcine manure markers were ubiquitous in rivers that drain agricultural and natural fields across the study region. This study provides baseline conditions on the state of watershed impairment, which can be used to develop best management practices that could improve water quality. Similar studies should be performed with higher spatial sampling density to elucidate detailed factors that influence the transport of manure constituents.