Litter Application Rate Research Articles

The morphophysiological and yield characteristics of biquinho amarelo pepper in response to bovine rumen residue and chicken litter in soil are dose dependent

In response to the growing demand for environmentally sustainable agricultural practices that enhance production efficiency, this study aimed to determine the optimal application rates of bovine rumen content (CBR) and chicken litter (CCL) as organic composts. Conducted in a controlled greenhouse environment, the research assessed the effects of various doses of these composts on soil chemical and microbiological properties and on the growth and productivity of yellow biquinho pepper (Capsicum chinense Jacq.). The results of this study confirm that organic composts improve soil health and increase the growth and productivity of yellow biquinho pepper. However, while CBR consistently enhances plant growth across a range of doses, CCL shows a dose-dependent response, with the highest fruit production achieved at an application rate of 73.92 Mg ha−1. Although this dose of CCL is beneficial for increasing yield, it also marks a threshold beyond which further increases may lead to negative effects such as nutrient saturation or salt accumulation, potentially resulting in soil toxicity. The study supports the use of CBR and CCL as effective soil conditioners and emphasizes the need to identify the optimal compost dose to efficiently harness the benefits of organic composts in sustainable agricultural practices.

Preferential flow of phosphorus and nitrogen under steady‐state saturated conditions

AbstractRepeated broiler litter application on agricultural lands can cause nutrient enrichment of subsurface effluent, especially with the existence of preferential flow through soil macropores. Previous studies quantifying soil macropores have not attempted to establish a connection of soil macropore characteristics with the subsurface nutrient (nitrogen [N] and phosphorus [P]) losses, across different topographical locations in the field. This study investigated the effect of broiler litter application and preferential flow on subsurface nutrient transport (N and P) at different topographical positions (upslope, midslope, and downslope) in a no‐till pasture field located in Alabama, USA. Twelve intact soil columns (150 mm id and 500 mm length) were used, and the nutrient leaching measurements from laboratory experiments were linked to soil macropore characteristics quantified using X‐ray computed tomography image analysis and solute transport modeling. Treatments included surface broadcast broiler litter (5 Mg ha−1, on dry basis) and unamended control. Leachates were analyzed for dissolved reactive P (DRP), total P (TP), and nitrate + nitrite‐N (NO3− + NO2−–N). The bromide breakthrough curves provided evidence of preferential flow in all columns. Litter application significantly increased leachate P concentrations, and average TP and DRP concentrations were significantly higher in the leachate from upslope columns compared to those at downslope location. The NO3−–N concentrations in leachate exceeded the US EPA drinking water standard of 10 mg L−1 in all the treatment columns. The highest flow‐weighted mean concentrations of TP and DRP, at 2.7 and 2.5 mg L−1, respectively, were recorded in the upslope columns. Soil physicochemical properties and nutrient leaching losses varied substantially across topographical positions, indicating a need for variable litter application rates to reduce P build‐up and subsequent leaching in vulnerable locations within the field. The relevance of the effect of topographic position on nutrient leaching found in this study should be further tested by investigating a wider range of slopes and soil types in pastures.

Managing cover crop C:N ratio and subsurface‐banded poultry litter rate for optimal corn yields

AbstractCover crops can be used to provide some of the nitrogen (N) needs of a cash crop to complement mineral fertilizers or manure, but there has yet been limited work to describe corn (Zea mays L.) yield as a function of cover crop quality and N inputs. We investigated the response of corn yield to gradients of both preceding cover crop C:N ratio and poultry litter (PL) application rates in Beltsville, MD during 2012–2014. To achieve different C:N ratios of the cover crops, hairy vetch (Vicia villosa Roth. "Groff") and cereal rye (Secale cereale L. "Aroostook") were seeded in a replacement series of six seeding rate proportions, resulting in shoot C:N ratios of 9.2:1 to 152:1 across years. For each hairy vetch/cereal rye sown proportions, PL was side‐dressed at corn V5–V8 stage in subsurface bands (SSB) at four targeted rates: Zero, P‐based (67 kg plant available nitrogen [PAN] ha−1), N‐based (135 kg PAN ha−1), and excess N and P (269 kg PAN ha−1). We found that corn yield followed a linear‐plateau relationship across these two dimensions. Within the linear region, each unit increase in log‐scaled cover crop C:N ratio resulted in a yield decrease of 2.56 ± 0.26 Mg ha−1 at a given rate of SSB PL. To optimize corn yields, we describe a model where each unit increase in log‐scaled cover crop C:N ratio required an additional 45.9 ± 6.22 kg PAN ha−1 from SSB PL. Yields following winter fallow were typically intermediate to the range of yields observed following the gradient of cover crop C:N ratios. We did not find significant differences in corn yield responses when comparing SSB PL to at‐planting incorporated or broadcast PL; we also found no significant differences between SSB PL and surface‐banded urea ammonium nitrate. Taken together, our approach of modeling yield response across two dimensions can be widely used to guide adaptive N management in subsequent cash crops following winter cover crops, thereby balancing both economic and environmental objectives in cover crop‐based cropping systems.

Broiler litter application rate and time impacts on corn ear mineral composition

AbstractThe nutrient composition of a corn (Zea Mays L.) ear impacts its nutritional value and potential use as human food and animal feed. Whether the application of broiler litter (BL) can enrich corn ears with supplied mineral elements compared to conventional fertilizers is not well studied. A 2‐year study investigated the mineral composition of corn ears as affected by nutrient source (BL or urea), application rate (0, 168, and 336 kg total N ha−1), and application time (single or split) at three locations in Alabama, USA. Corn ear samples were collected at physiological maturity each year and analyzed for the total nutrient contents of 11 mineral elements. Regardless of application rate and application time, BL did not increase any elemental concentrations in the corn ear. Corn fertilized with urea had the highest corn ear concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), zinc (Zn), manganese (Mn), iron (Fe), and copper (Cu) across all locations. Corn ear N concentration depended on the soil's level of plant‐available N (PAN). Corn ear concentrations of P, K, and other mineral elements were not dependent on their soil levels but the corn ear N concentration. Thus, growing corn with an adequate supply of PAN in soil, irrespective of the source ensures maximum accumulation of corn ear N and other mineral elements.

The Role of Poultry Litter and Its Biochar on Soil Fertility and Jatropha curcas L. Growth on Sandy-Loam Soil

Low agricultural output and a decline in plant-available nutrient content in soil pose significant challenges to developing countries. To test the hypothesis that poultry litter and its biochar improve soil quality, nutrient status, and plant growth, a greenhouse pot experiment with sandy-loam soil was conducted. Selected application rates of poultry litter (0, 15, 30, 60, and 120 g/kg) and its biochar pyrolyzed at 350 °C and 600 °C were used. With the addition of organic amendments, Jatropha plant height, leaf number, and stem diameter improved significantly, as did soil fertility indicators (pH, organic matter content, cation exchange capacity, and plant-available nutrients). When compared to the control, increased application rates ranging from 60 g/kg to 120 g/kg significantly improved soil properties and plant growth. PL (Poultry litter)- and BC350 (Biochar produced at 350 °C)-treated soil outperformed other organic amendments in terms of soil quality, nutrient status, and plant growth. Soil pH, CEC, and OM were found to be positively correlated with available plant nutrients, with PL-treated soils having higher levels of plant available nutrients. Because the properties of the feedstocks complement each other, combined organic amendments improved studied parameters, particularly PLBC600 (Poultry litter mixed with biochar produced at 600 °C) compared to BC600 (Biochar produced at 600 °C). Increased application rates of pure and combined feedstock effectively increased soil fertility and Jatropha growth; however, lower temperature biochar is recommended for use as a soil organic amendment.

Twenty‐year phosphorus trends in forage systems receiving aluminum sulfate‐treated poultry litter

AbstractAdding aluminum sulfate or alum to poultry litter is a best management practice (BMP) that reduces ammonia emissions and P runoff and leaching, although its long‐term effects on forage growth and P uptake are largely unknown. The objective was to determine if reducing soluble P in litter with alum would result in forage P deficiencies or reduce yields. A 20‐yr study was conducted to determine effects of four rates of alum‐treated litter, untreated litter, and ammonium nitrate (NH4NO3), as well as an unfertilized control on tall fescue (Festuca arundinacea Schreb.) yield and P uptake. Phosphorus uptake increased as litter rates increased for both sources but was greater (P ≤ .05) for untreated litter, likely owing to high water‐extractable P in soil. Over 20 yr, both litter sources had greater P uptake than NH4NO3. Average annual yields by fertilizer source across rates were 6.92, 6.64, 5.10, and 3.38 Mg ha–1 for alum‐treated litter, untreated litter, NH4NO3, and the control, respectively. Forage yields increased with litter application rate, but there was no difference due to litter source, whereas yields were 34% lower with NH4NO3 due to soil acidification and forage P deficiency (≤0.2% P). Multiple regression indicated tall fescue P uptake was affected by total P application rate and water‐extractable phosphorus (WEP), whereas yields were influenced by N rates, Mehlich III P levels, soil pH, and precipitation. These results indicate that amending soils with alum‐treated litter does not adversely affect tall fescue yields or P utilization, therefore alum is a sustainable BMP in pasture systems.

Comparative analysis of leaf litter decomposition and nutrient release patterns of bamboo and traditional species in agroforestry system in Ghana

Understanding leaf litter decomposition dynamics is imperative owing to nutrient release rates and synchronization. The overarching aim is to sustainably manage agroforestry systems and ensure environmental integrity. Therefore, this study aimed at determining the decomposition and nutrient release of leaves of different bamboo species (Oxytenanthera abyssinica, Bambusa balcooa, Bambusa vulgaris), rarely used woody perennials in agroforestry system in Ghana, and compared with commonly used agroforestry species; Albizia lebbeck, Senna siamea, Gliricidia sepium, Leucaena leucocephala, and Eucalyptus grandis. Litterbag technique was used and freshly fallen leaves of the species (equivalent to 100 g on a dry weight basis) were collected and placed into 30 cm × 45 cm nylon litterbags with a 2-mm mesh size. The weight of the samples in the litterbags was based on local plant litter application rates (5 t dry matter ha1) for maize production in the study location. There was a total of 216 litterbags (27 per species) for the study. Eight transects spaced at 1.0 m apart were laid in a randomized complete block design and twenty-seven litter bags spaced 0.5 m apart were placed on each transect. The litterbags were buried at 2 cm depth and three samples of each species were retrieved and weighed for 210 days to determine weight loss and nutrient release. Compared with Oxytenanthera abyssinica (8 weeks) and Senna siamea (6 weeks) half-life, rate of decomposition was analogous and higher than the other species. Further, Bambusa balcooa and the other non-bamboo species showed similar rate of decomposition. However, Bambusa vulgaris had marginally slower rate of decomposition compared to the traditional species. The highest rate of N, P, K and Ca release was recorded for Albizia lebbeck. Nonetheless, rates of P, Ca and Mg release were comparable to the other non-bamboo species. Eucalyptus grandis and Bambusa vulgaris also showed dominance in initial nitrogen and lignin concentrations and release. Therefore, with the observed substantial and comparable litter quality and decomposition rate among the species, it may be imperative to consider using the bamboo species for soil amendment and green manure in agroforestry system.

Effects of broiler litter application rate and time on corn yield and environmental nitrogen loss

AbstractUse of broiler litter (BL) for agronomic purposes requires balancing the amount of nitrogen (N) needed to maximize crop yield while reducing environmental N footprints. This 2‐yr study (2018–2019) compared the effects of N source (BL or urea), application rate [0, 168, and 336 kg total N ha–1), and application timing (single or split) on corn (Zea mays L.) yield and environmental nitrogen loss (ENL) on three Alabama soil types. A field‐scale partial N budget was developed by accounting for known N inputs and outputs. The difference between the input and output in the partial N budget was considered as ENL, which comprised of N losses via runoff, leaching, volatilization, and denitrification. Application of BL increased corn yield relative to urea at only one site. At the responsive site, BL application rate had no significant effect on corn yield, but pre‐plant single application of BL produced 52% greater corn yield compared with split application. At other two sites where yield was lower for corn receiving BL, corn yield increased significantly with increasing BL application rate. Total N loss to the environment ranged between 32 and 52% of the N input. The influence of N source on ENL varied by site however losses increased with increasing N fertilization rates. Application timing did not influence ENL at two of three sites. This study showed that a lower application rate (168 kg ha–1) of BL prior to planting was a better management strategy for increasing corn yield, while reducing environmental N loss.

Long-term effect of poultry litter application on phosphorus balances and runoff losses.

Assessment of annual and cumulative impacts of phosphorus (P) management strategies at field and watershed scales is needed to improve crop use efficiency and minimize environmental impacts. The objectives of this study were (a) to assess relationships among P balance, soil test P (STP) concentration, and runoff dissolved reactive P (DRP) concentration from fields receiving different poultry litter application rates (0.0-13.4 Mg ha-1 ) and (b) to determine the effect of long-term poultry litter application to fields on watershed DRP loss. Nutrient management practices, crop yield, STP, and runoff losses were assessed from nine fields and two watersheds located near Riesel, TX, from 2000 to 2015. Field-scale P balances were largely controlled by P application rate and exhibited a positive relationship with STP and runoff DRP flow-weighted mean concentration. Using a before-after control-impact experimental design that included monitoring at both field and watershed scales showed the influence of field P management on watershed DRP loss varied according to both source (i.e., P application rate, impacted area) and transport (i.e., hydrological connectivity) factors. Increased risk of watershed DRP loss was observed during wet years and years with two poultry litter applications to fields within the watershed. The percentage of the total watershed area receiving high rates of poultry litter also played a critical role in determining the risk of DRP loss. Findings highlight the impact of long-term P management strategies on DRP loss at both field and watershed scales and show the importance of incorporating hydrologic connectivity when assessing conservation effects on water quality.

Influence of Inorganic Fertilizer (NPK 15:15:15) and Cacao (Theobroma cacao L) Leaf Litter Application Rates on Cowpea (Vigna unguiculata L.) Performance in the Tropics

Influence of inorganic fertilizer (NPK 15:15:15) and cacao (Theobroma cacao L.) leaf litter application rates on cowpea (Vigna unguiculata L.) performance in the tropics was studied for 24 months (January, 2017 – December, 2018) at Cocoa Research Institute of Nigeria (CRIN) Ibeku Sub-Station, Umuahia, Nigeria. Three 3 x 3 factorial experiments, each in a Randomized Complete Block Design (RCBD) with three replicates/blocks were used to study the responses of cowpea to three NPK 15:15:15 fertilizer rates 0 kg, 500 kg and 1000 kg ha-1 represented by (Factor F) F0, F1 and F2, respectively, and cocoa leaf litter rates 0 t, 10 t and 20 t ha-1 which were also represented by Lo, L1 and L2 (Factor L), respectively. The results obtained from the study show that the application of either 10 or 20 t ha-1 cocoa leaf litter alone or complementary application of either 10 or 20 t ha-1 cocoa leaf litter plus 500 or 1000 kg ha-1 NPK 15:15:15 fertilizer significantly increased the various cowpea growth and yield components than the fertilizer rates alone. The treatment without fertilizer and leaf litter, i.e. topsoil only (F0L0) gave significantly the least cowpea growth and yield components. The highest values were obtained with the application of 1000 kg ha-1 NPK 15:15:15 fertilizer with 20 t ha-1 cocoa leaf litter (F2L2). The cowpea crop performance in terms of growth, yield and yield components over the study periods, 2017 and 2018 were statistically similar. Therefore, the inclusion of leaf litter has greater potential for improving cowpea yield than when fertilizer was used alone. Leaves are potential sources of valuable nutrients providing a high quality of organic matter, which should be returned to the soil.

Influence of Inorganic Fertilizer (NPK 15:15:15) and Cacao (Theobroma cacao L) Leaf Litter Application Rates on Cowpea (Vigna unguiculata L.) Performance in the Tropics

Influence of inorganic fertilizer (NPK 15:15:15) and cacao (Theobroma cacao L.) leaf litter application rates on cowpea (Vigna unguiculata L.) performance in the tropics was studied for 24 months (January, 2017 – December, 2018) at Cocoa Research Institute of Nigeria (CRIN) Ibeku Sub-Station, Umuahia, Nigeria. Three 3 x 3 factorial experiments, each in a Randomized Complete Block Design (RCBD) with three replicates/blocks were used to study the responses of cowpea to three NPK 15:15:15 fertilizer rates 0 kg, 500 kg and 1000 kg ha-1 represented by (Factor F) F0, F1 and F2, respectively, and cocoa leaf litter rates 0 t, 10 t and 20 t ha-1 which were also represented by Lo, L1 and L2 (Factor L), respectively. The results obtained from the study show that the application of either 10 or 20 t ha-1 cocoa leaf litter alone or complementary application of either 10 or 20 t ha-1 cocoa leaf litter plus 500 or 1000 kg ha-1 NPK 15:15:15 fertilizer significantly increased the various cowpea growth and yield components than the fertilizer rates alone. The treatment without fertilizer and leaf litter, i.e. topsoil only (F0L0) gave significantly the least cowpea growth and yield components. The highest values were obtained with the application of 1000 kg ha-1 NPK 15:15:15 fertilizer with 20 t ha-1 cocoa leaf litter (F2L2). The cowpea crop performance in terms of growth, yield and yield components over the study periods, 2017 and 2018 were statistically similar. Therefore, the inclusion of leaf litter has greater potential for improving cowpea yield than when fertilizer was used alone. Leaves are potential sources of valuable nutrients providing a high quality of organic matter, which should be returned to the soil.

Legume Cover Crops Reduce Poultry Litter Application Requirements in Organic Systems

Organic farmers are challenged by increasing soil P levels resulting from the use of manure to meet cash crop N needs. The use of a legume cover crop may address this challenge. In a 2‐yr study at three organic production sites in Maryland, we examined the combination of a winter annual legume cover crop (hairy vetch, crimson clover, Austrian winter pea, and a no‐cover control) at three poultry litter (PL) application rates (to meet the N requirement of corn, to replace P removed by corn grain harvest, and a no‐PL control). Cover crop biomass varied by site and by year, ranging from about 600 to 6100 kg ha–1 for crimson clover. Cover crop N accumulation ranged from 15 to 169 kg N ha–1. Corn yields, which ranged from 2.9 to 14.2 Mg ha–1, tended to be lowest in the control (0 PL) no‐cover treatments and similar in the N‐based and P‐based treatments irrespective of the cover crop species. These results indicate that when legume cover crops are used, PL can be applied at a P‐replacement rate on sites with a history of PL application to meet crop production and environmental stewardship goals.Core Ideas Legume cover crop N accumulation ranged from 15 to 169 kg N ha–1. Corn yield after legume crops was not affected by poultry litter application rate. Legume cover crops provide opportunity to reduce poultry litter application rates.

The Role of Field-Scale Management on Soil and Surface Runoff C/N/P Stoichiometry.

Agricultural runoff is an important contributor to water quality impairment. This study was conducted to evaluate the potential role of field-scale management on carbon (C), nitrogen (N), and phosphorus (P) stoichiometry in soils and runoff from agricultural fields. Cultivated and pasture fields at the Riesel watersheds in central Texas were used for this analysis, and nutrients were transformed to evaluate relative to the Redfield ratio (106 C/16 N/1 P). Using the Redfield ratio, all soil samples were P depleted relative to C and N. The majority of stormflow and baseflow runoff samples contained 9 to 19% Redfield N relative to C and P. Shifting from inorganic fertilizer application to poultry litter as a fertilizer source resulted in increased absolute C, N, and P concentrations in stormflow and baseflow runoff. Increasing rates of poultry litter application increased the Redfield P relative to Redfield C, whereas Redfield N remained relatively constant at roughly 9 to 11% in stormflow runoff from cultivated fields. This study shows how land use and management can affect C/N/P stoichiometry in stormflow and baseflow runoff.

Optimum Poultry Litter Rates for Maximum Profit versus Yield in Cotton Production

Cotton (Gossypium hirsutum L.) lint yield responds well to increasing rates of poultry litter fertilization, but little is known of how optimum rates for yield compare with optimum rates for profit. The objectives of this study were to analyze cotton lint yield response to poultry litter application rates, determine and compare rates that maximize lint yield (PLy) vs. profit (PLp), and identify a practical approach for estimating PLp. Cotton planted on two farms that used conventional and no‐tillage systems were fertilized with seven target rates of litter from 0 to 13.5 Mg ha−1 or with a farm standard treatment receiving synthetic fertilizers (Std). The PLy and PLp for each year and farm were determined from current cotton and poultry litter prices and response curves fitted into lint yield and actual applied litter rates. The results showed that cotton lint yield peaked at an average across years of 1430 kg ha−1, with 11.1 Mg ha−1 PLy in the conventional tillage system and at 1354 kg ha−1 with 13.2 Mg ha−1 PLy in the no‐till system. These peak yields exceeded the respective Std treatment yields but were not the most profitable. Maximum profit in both tillage systems was achieved with 7.8 Mg ha−1 PLp, which resulted in lint yields of 1367 and 1253 kg ha−1 in the conventional and no‐till systems, respectively. The PLp in both systems was similar to the poultry litter rate that resulted in lint yield equal to the Std (PLs), which suggests that applying litter to provide plant available N equal to the farm standard practice for synthetic N fertilizers is a practical method for estimating PLp.

Short-term nitrogen dynamics in soil amended with poultry litter containing woodchip bedding

Concurrent N mineralization and immobilization in soils receiving poultry litter containing woodchip bedding may reduce synchrony between the short-term N supply and crop N demand. Therefore, we used soil chemical tests, ion exchange membranes, and wheat N uptake to assess N dynamics in a poultry-litter-amended soil. Air-dried soil was thoroughly mixed with five poultry litter rates (50, 100, 150, 200, or 250 mg total N kg−1) and preincubated for 7 d in a controlled environment chamber. After preincubating, soil was placed in 10-cm-diameter pots and planted with spring wheat (Triticum aestivum ‘Wilkin’), or left unplanted and monitored with anion and cation exchange membranes for 45 d. Soil nitrate (NO3-N) concentration increased with poultry litter application rate at the end of the preincubation period, but subsequent wheat N uptake did not, suggesting that little net N mineralization occurred during the 45 d of wheat growth. The membrane data indicated a shift from net N immobilization during the early part of the wheat growth period to net mineralization during the latter portion of the wheat growth period. We conclude that alternating N mineralization and immobilization in soils receiving poultry litter containing woodchip bedding limited the short-term N supply to wheat.

Fate and Risk Assessment of Arsenic Compounds in Soil Amended with Poultry Litter Under Aerobic and Anaerobic Circumstances

Poultry litter and bedding materials generated from laying chicken farm often contain high levels of arsenic when roxarsone is included in feed to combat disease and improve egg production. This study was conducted to determine the fate and ecological risk of arsenic species in poultry litter which applied to agricultural field. Three poultry litter application rates (0, 10, 60 % dry weight) were used to amend soil samples under anaerobic and aerobic circumstances, respectively, incubated at 30 % moisture content for 110 days. Experiment indicated that under anaerobic circumstance, As(V) and As(III) decreased in treatments applied 60 and 10 % rates within initial 7 days, subsequently methylated arsenic displayed increasing, suggesting biotic activity transformed inorganoarsenical to methylated arsenic species. In contrast, As(V) dropped in the first 7 days but increased thereafter under aerobic circumstances, with methylated arsenic increasing, implying abiotc and biotic activities enhanced arsenic speciation. Based on different arsenic species, we evaluated their ecological risk in poultry litter respectively. It was found that ecological risks under anaerobic circumstance were higher than under aerobic circumstance of the same poultry litter rates, and higher poultry litter rates applied to soil would bring about higher ecological risk. We suggest that poultry litter should be disposed at low rate (approximately 10 %) and applied to soil surface to create aerobic circumstance for the initial 2 months time, but should be buried into a deeper depth thereafter.

Nutrient cycling in an agroforestry alley cropping system receiving poultry litter or nitrogen fertilizer

Optimal utilization of animal manures as a plant nutrient source should also prevent adverse impacts on water quality. The objective of this study was to evaluate long-term poultry litter and N fertilizer application on nutrient cycling following establishment of an alley cropping system with eastern black walnut (Juglans nigra L.), pecan [Carya illinoensis (Wangenh.) K. Koch], and northern red oak (Quercus rubra L.) trees and orchardgrass (Dactylis glomerata L.). One half of a 4.25-ha site in northwestern Arkansas USA received broadcast applications of 3.9–6.7 Mg ha−1 fresh poultry litter and the other half 50–76 kg ha−1 N as NH4NO3 fertilizer each spring from 2001 to 2008. Macronutrient (N, P, K, Ca, Mg, and S) and micronutrient (Na, Fe, Mn, Zn, and Cu) concentrations in soil, forage, and tree leaf tissue were monitored along with NO3-N in soil water and groundwater. Poultry litter application resulted in significantly increased concentrations of each macronutrient except S with increases from 6.3 (N) to 121 % (P). Nitrogen fertilizer application resulted in decreased concentrations from 2.1 (N) to 60.9 % (S) for all macronutrients except Ca. Patterns of nutrient content in forage and tree leaf tissue did not generally follow patterns of soil nutrient concentrations suggesting nutrient sufficiency in most years and that climate and plant growth had a greater effect on nutrient uptake. Soil P with litter application increased 41.3 mg kg−1 over 7 years (from 34.1 to 75.4), which may necessitate a lower litter application rate to avoid excessive P runoff.

Influence of farm yard manure, poultry manure and forest litter on copper solubility in soil and uptake by Phaseolus vulgaris

AbstractLong term and intensive use of copper‐based fungicides on coffee farms may contaminate soils with copper. The legacy of copper pollution may pose the risk of contaminating food crops cultivated on these soils. A randomized block design field experiment at Kilimanjaro, Tanzania was designed to investigate the effects of different application rates of cattle manure, poultry manure and forest litter on aqua regia, EDTA and CaCl2 extractable copper in soils and copper uptake by bean plants grown on this long‐term copper‐contaminated soil (more than 50 yr of copper application). It was important to examine the potential of the organic amendments in mobilizing or immobilizing copper and assess the risks of contaminating bean crops at a farm, where the application of organic amendments was common practice. At harvest, rhizosphere soils were collected and analysed. The soils were found to have large concentrations of copper, greatly exceeding international standard levels. Poultry manure applied at 40 tons/ha significantly increased CaCl2 extractable copper compared with the control treatment. Organic carbon, cation exchange capacity, EDTA extractable copper, aqua regia extractable copper and copper concentrations in bean seeds or leaves were not significantly changed by the organic matter treatments. The concentration of copper was significantly less in bean seeds than in bean leaves (P < 0.01). The bean plants did not take up excessive quantities of copper, and therefore, the risk of copper contamination of bean crops in this farm appears to be small.

Factors affecting arsenic and copper runoff from fields fertilized with poultry litter.

Arsenic (As) and copper (Cu) runoff from fields fertilized with poultry litter has received increasing attention in recent years, although it is not known if heavy metal runoff from poultry litter poses a significant threat to the environment. The objective of this study was to determine the main factors affecting As and Cu concentrations in runoff water from pastures receiving poultry litter applications. Rainfall simulation studies were conducted to determine the effects of the following treatments on metal runoff: (i) aluminum sulfate (alum) additions, (ii) diet modification using phytase or high available phosphorus corn, (iii) fertilizer type, (iv) poultry litter application rate, and (v) time until the first runoff event occurs after poultry litter application. Results showed that alum additions to poultry litter significantly decreased As and Cu concentrations in runoff water. Copper concentrations were highest in runoff from poultry litter from birds fed phytase diets compared with other diets; however, this effect may have been a result of wet storage conditions rather than diet. Triple superphosphate applications resulted in the lowest heavy metal concentrations in runoff water among all fertilizer treatments, while normal poultry litter resulted in the highest concentrations. Arsenic and Cu concentrations increased in runoff water as poultry litter application rates increased and decreased with increasing time until the first runoff event. These data indicate that adding alum to poultry litter, a cost-effective best management practice, which also results in lower P runoff and ammonia emissions, may also be an effective tool in reducing metal runoff.

Nutritional and physical properties of organic Beauregard sweet potato [Ipomoea batatas (L.)] as influenced by broiler litter application rate.

Organic farming has been on an upward trend in recent years. However, the manures used like broiler litter have variable nutrient content, making it important to establish optimal application rate, for maximum crop yield and quality. Additionally, some states like Alabama restricts the amount of broiler litter to control excessive nutrients accumulation which can lead to surface and ground water contamination. The current study evaluated the effect of broiler litter at rates 0, 0.5, 1, 2, and 3 t ha−1 (treatments T0, T0.5, T1, T2, and T3), on the nutritional and physical properties of Beauregard sweet potato. Analyses were performed to determine moisture, ash, fiber, vitamin C, and β-carotene contents using oven, muffler furnace, dye, and spectrophotometric methods; texture; and color using compressive strength and L, a, b system, respectively. Ash content of the samples ranged from 0.9% to 1.4% with a very strong positive linear correlation (r = 0.9) to the broiler litter rate. However, vitamin C had a quadratic relationship with the broiler litter rate with a peaking at T0.5 (15.5 mg/100 g). The yellow color (b-value) also had a strong linear relationship with the broiler litter rate (r = 0.86). However, the other measures showed moderate, weak, or negligible correlations to the broiler litter level. T0.5 had the highest β-carotene (262.0 μg/g), dry matter contents and had the most firm (0.040 kN) sweet potatoes with the deepest orange color (L = 60.7). Based on the study's findings, 0.5 t ha−1 appeared to be appropriate level of broiler litter, which is consistent with Alabama's law and is also advantageous in terms of low cost of farming practices and water pollution reduction.