Effect of fall tillage following soybeans on organic matter losses in snowmelt

In a corn–soybean rotation, maintaining crop residue on the soil surface is a challenge following soybeans. Often farmers are encouraged not to till the soil following a soybean crop in order to maximize the amount of residue at the soil surface. In this study we evaluated the effect of this practice compared to fall moldboard plowing on snowmelt runoff and losses of total solids (TS) and organic carbon (using oxygen demand in runoff as a surrogate). A paired watershed approach was used to evaluate the effect of these management practices. Individual hydrographs were compared and contaminant losses in runoff calculated. Results show that snowmelt runoff and the associated losses of total solids, chemical oxygen demand (COD), and biochemical oxygen demand (BOD) were less with fall moldboard plowing compared to no fall tillage following soybean (0.22 cm, 1.9 kg ha⁻¹, 0.81 kg ha⁻¹, 74 g ha⁻¹, reduction in median value per melt cycle, respectively). In areas where snowmelt runoff is an important component of annual runoff, some tillage in the fall would be preferable to no-tillage in order to reduce snowmelt runoff losses.     

Detrimental effects of pharmaceutical industrial waste on microorganisms

Pharmaceutical industrial waste was collected from Ghaziabad (Cooper Pharma Ltd.) and analyzed for color, odor, specific gravity, turbidity, pH, total solids, suspended solids, dissolved solids, volatile solids, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), organic and inorganic nitrogen, sulfur, chlorides, sulfates and phosphates. The detrimental effects of industrial waste on microorganisms were studied in the system with lower and higher volumes of the wastes (0.5–12 ml) using glucose substrate as a source of carbon for microorganisms. The cultures of saprophytic and nitrifying bacteria were grown from sewage and pea gravel, respectively, and tested for their nature.     

Constructed Wetlands Treating Runoff Contaminated with Nutrients

The aim was to assess the role of Phragmites australis (Cav.) Trin. ex Steud. in experimental, mature, and temporarily flooded vertical flow wetland filters treating urban runoff rich in organic matter. During the experiment, ammonium chloride was added to sieved concentrated road runoff to simulate primary treated urban runoff contaminated with nitrogen. Five days at 20°C N-allylthiourea biochemical oxygen demand (BOD) and chemical oxygen demand removal efficiencies were relatively lower for planted than unplanted filters. Moreover, there was no significant difference for BOD removal for all filters under fluctuating inflow concentrations of sulfate. The nitrogen removal performances of planted filters were more efficient and stable throughout the seasons compared to those of unplanted filters. A substantial load of nitrogen (approximately 500 mg per filter) was removed by harvesting P. australis. Plant uptake was the main removal mechanism for nitrogen during high concentrations (10 mg/L) of ammonia-nitrogen in the urban runoff.     

Electrochemical Production of Ferrate (Iron VI): Application to the Wastewater Treatment on a Laboratory Scale and Comparison with Iron (III) Coagulant

This paper presents a comparative study of the performance of ferrate(VI), FeO ₄ ^2? , and ferric, Fe(III), towards wastewater treatment. The ferrate(VI) was produced by electrochemical synthesis, using steel electrodes in a 16 M NaOH solution. Domestic wastewater collected from Hailsham North Wastewater Treatment Works was treated with ferrate(VI) and ferric sulphate (Fe(III)). Samples were analysed for suspended solids, chemical oxygen demand (COD), biochemical oxygen demand (BOD) and P removal. Results for low doses of Fe(VI) were validated via a reproducibility study. Removal of phosphorous reached 40% with a Fe(VI) dose as low as 0.01 mg/L compared to 25% removal with 10 mg/L of Fe(III). For lower doses (<1 mg/L as Fe), Fe(VI) can achieve between 60% and 80% removals of SS and COD, but Fe(III) performed even not as well as the control sample where no iron chemical was dosed. The ferrate solution was found to be stable for a maximum of 50 min, beyond which Fe(VI) is reduced to less oxidant species. This provided the maximum allowed storage time of the electrochemically produced ferrate(VI) solution. Results demonstrated that low addition of ferrate(VI) leads to good removal of P, BOD, COD and suspended solids from wastewater compared to ferric addition and further studies could bring an optimisation of the dosage and treatment.     

Empirical analysis and prediction of nitrate loading and crop yield for corn-soybean rotations

Nitrate nitrogen losses through subsurface drainage and crop yield are determined by multiple climatic and management variables. The combined and interactive effects of these variables, however, are poorly understood. Our objective is to predict crop yield, nitrate concentration, drainage volume, and nitrate loss in subsurface drainage from a corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) rotation as a function of rainfall amount, soybean yield for the year before the corn-soybean sequence being evaluated, N source, N rate, and timing of N application in northeastern Iowa, U.S.A. Ten years of data (1994-2003) from a long-term study near Nashua, Iowa were used to develop multivariate polynomial regression equations describing these variables. The regression equations described over 87, 85, 94, 76, and 95% of variation in soybean yield, corn yield, subsurface drainage, nitrate concentration, and nitrate loss in subsurface drainage, respectively. A two-year rotation under average soil, average climatic conditions, and 125 kg N/ha application was predicted to loose 29, 37, 36, and 30 kg N/ha in subsurface drainage for early-spring swine manure, fall-applied swine manure, early-spring UAN fertilizer, and late-spring split UAN fertilizer (urea ammonium nitrate), respectively. Predicted corn yields were 10.0 and 9.7 Mg/ha for the swine manure and UAN sources applied at 125 kg N/ha. Timing of application (i.e., fall or spring) did not significantly affect corn yield. These results confirm other research suggesting that manure application can result in less nitrate leaching than UAN (e.g., 29 vs. 36 kg N/ha), and that spring application reduces nitrate leaching compared to fall application (e.g., 29 vs. 37 kg N/ha). The regression equations improve our understanding of nitrate leaching; offer a simple method to quantify potential N losses from Midwestern corn-soybean rotations under the climate, soil, and management conditions of the Nashua field experiment; and are a step toward development of easy to use N management tools.     

Rotation and tillage effects on soil organic carbon sequestration in a typic Hapludalf in Southern Ontario

Increased use of conservation tillage is being considered as a way to sequester atmospheric C in the soil. However, little information exists on the effect of rotation and its interaction with tillage on soil organic carbon (SOC). A research trial with combinations of rotations and tillage treatments was sampled 20 years after its establishment to assess the effects on SOC sequestration in a typic Hapludalf in southern Ontario, Canada. The cropping treatments included continuous corn (zea mays L.), six rotations comprised of 2 years of corn following 2 years of another crop or crop sequence, and continuous alfalfa (Medicago sativa L.). Each rotation was split into either fall moldboard plow (MP) or fall chisel plow (CP) treatments. Continuous alfalfa was plowed and replanted every 4 years. Soil samples were taken incrementally to a depth of 40 cm and SOC and bulk density determined. The average SOC concentration (0–40 cm) was greatest in continuous alfalfa (18.0 g C kg⁻¹). The treatments of soybean (Glycine max L.Merr.)+winterwheat (Triticum aestivum L.) or barley+barley (Trifolium pratense L.) (interseeded with red clover) followed by 2 years of corn had higher SOC concentrations (17.2–17.3 g C kg⁻¹) than continuous corn and the treatments of 2 years of corn following 2 years of alfalfa or soybean (16.4–16.5 g C kg⁻¹). The rotation of 2 years of barley followed by 2 years of corn had the lowest SOC concentrations (15.2 g C kg⁻¹). On an equivalent mass basis, the rotations of soybean+winterwheat or barley+barley (underseeded with red clover) followed by 2 years of corn, had 2–9 Mg ha⁻¹ more C than the other corn-based rotations. Including red clover in the winter wheat seemed to accelerate the rate of C mineralization compared to winter wheat without red clover; whereas interseeding red clover with barley increased SOC contents compared to excluding red clover in the barley rotation. More SOC was found in the top 10 cm and less in the 10–20 cm depth of the CP than in the MP soils. However, the CP did not increase the SOC content (0–20 cm) above that of MP indicating that this form of reduced tillage did not increase C sequestration in any of the rotations on this soil.     

Response of Winter Manure Application on Surface Runoff Water Quantity and Quality from Small Watersheds in South Dakota

Manure application on frozen soil, which is a common practice in the upper Midwest of USA, results in degraded soil and water quality. During snowmelt or precipitation events, water runoff carries nutrients into nearby streams and impairs the water quality. There is a need, therefore, to identify improved management of manure application in the soils. This study was conducted to assess water quality impacts associated following manure application during winter months when soil is completely covered with snow. The study site included three watersheds, named south (SW), east (CW), and north (NW) managed with a corn (Zea mays L.)-soybean (Glycine max L.) rotation located in South Dakota. The SW and NW were used as treatment, and CW as the control watershed. The treatments included manure application on the upper half of the SW and lower half of the NW, and CW received no manure application. This study showed that manure improved soil properties including infiltration rate and organic matter. Nitrogen and phosphorus losses in the surface runoff were higher from NW compared to that of SW. The CW had similar nutrient losses compared to the NW with slight differences. It can be concluded that maintaining a setback distance can help in improving the environmental quality as well as managing the agricultural wastes during the winter months.     

Plant nutrient losses in runoff from conservation tillage corn

Conservation tillage in north Mississippi, U.S.A., reduced total (sum of solution and sediment) plant nutrient losses in runoff from corn, even though solution nitrogen (N) and phosphorus (P) concentrations in runoff were greater than from conventional-till and sediments were enriched severalfold in N and P. Plant nutrient losses were reduced by conservation tillage because of the significant reductions in soil loss. Soil losses from corn grown for grain were reduced more than 92% by reduced and no-till practices. Corresponding total losses of N and P were reduced about 70 and 80%, respectively.Conservation tillage reduced plant nutrient losses associated with sediments but increased solution P concentrations and losses in runoff. Solution P concentrations and losses, which were related to crop management, decreased in the following order: no-till corn (grain) ? no-till corn (silage) > reduced-till corn (grain) > conventional-till corn (grain) > conventional-till corn (silage). Solution P concentrations and losses in runoff increased with an increase in crop residues left on the soil surface after harvest and with a decrease in annual soil loss.     

A conservation tillage research update from the Coastal plain soil and water conservation research center of South Carolina: A review of previous research

In the U.S. Southeastern Coastal Plains conservation tillage (CT) became useful as a management system with the development of in-row subsoiling systems capable of planting into heavy residues. Research priorities associated with the development of CT included: reducing cover crop water loss, improving stand establishment, assessing nutrient and water management requirements, determining optimal subsoiling strategies, understanding long-term conservation tillage effects on soil properties, evaluating the interaction of crop residue removal with tillage systems, and documenting tillage impact on pests and beneficial organisms. Since the late 1970s the Coastal Plains Soil and Water Conservation Research Center in Florence, SC has made a concerted effort to study these interactions and alleviate them as obstructions to the use of CT management. These studies showed that for Coastal Plain soils such as Norfolk sandy loam (fine-loamy, siliceous thermic, Typic Paleudults) winter cover crops such as rye (Secale cereale L.) desiccated the soil profile by evapotranspiration in the spring. This delayed emergence and early season growth of corn (Zea mays L.) but not full-season soybean (Glycine max (L.) Merr.). Conservation tillage helped manage soil strength by gradually increasing soil organic matter content, restricting traffic patterns and maintaining higher soil water contents. Laboratory studies demonstrated a negative correlation (R²=0.85) between proctor soil strength and organic matter content. Conservation tillage affected nematode, Bradyrhizobium japonicum and Heliothis species populations. Alternate cropping systems using rapeseed (Brassica napus L.) as a winter crop or sunflower (Helianthus annuus L.) either before soybean or after corn provided crop cover against potential soil loss from late autumn through early spring, when bare soil is exposed to intense rainfall. Water quality questions associated with CT have been raised but remain unanswered. Although CT can reduce runoff and erosion, the crop residues can support higher insect populations and pathogen inoculum levels, and thus prompt greater pesticide use. Quantifying relationships between soil strength, macropore formation and persistence, and water infiltration with surface and subsurface water quality is the focus of new long-term evaluations. The findings of these studies, published to date, are summarized in this paper.     

Nonpoint source loading of phenolic acids from decomposing crop residue

Two adjacent, but separate, watersheds were equipped to quantify the total volume of runoff water and to collect an integrated water sample. One watershed was planted with corn (Zea mays L.) using no-tillage (NT) management and barley (Hordeum vulgare L.) as a cover crop or left in corn stubble. The other watershed was planted with corn using conventional tillage (CT) management. Runoff water sampled between 1979 and 1983 was analyzed for total phenolic acids and phytotoxicity to turnip (Brassica rapa L.). The volume of runoff water was reduced with NT management, but the concentration and total loading of phenolic acids were greater in runoff water from the NT watershed compared to that found in runoff water from the CT watershed. There was no clear relationship between phenolic acid concentration in runoff and turnip radicle length; however, the runoff sample with the greatest concentration of phenolic acids (18 June 1979; 65 ppm phenolic acids) caused the greatest inhibitions of turnip radicle growth.     

Earthworm contributions to soil nitrogen supply in corn-soybean agroecosystems in Quebec, Canada

Accurately quantifying the soil nitrogen(N) supply in crop fields is essential for enabling environmentally sustainable and economically profitable crop production. It requires using field-based methods to account for the contribution of soil biota, including earthworms, to N mineralization in temperate agroecosystems. The direct contribution of earthworms to the soil N cycle is the N they release throughout their life and after death, and it can be estimated using the secondary production method. This study was conducted in 2014 and 2015 in two adjacent fields with annual corn-soybean rotation in Ste-Anne-de-Bellevue, Quebec, Canada. The cumulative biomass of Aporrectodea spp. in two no-till corn-soybean agroecosystems was determined, and the direct N flux from these earthworms was estimated during the corn and soybean phases of the rotation. Secondary production was estimated by sampling earthworms biweekly during April–June and September–November and inferring the change in earthworm biomass between sampling dates using a size frequency calculation. The N flux was calculated as the sum of the N released through excretion, during periods when earthworms were active, and from mortality. The secondary production of the Aporrectodea population was estimated to be 8–43 g ash-free dry weight m~(-2) year~(-1), and the N flux was 22–105 kg N ha~(-1) year~(-1). The N flux was higher at the early vegetative growth stage, which is a period of high N demand for corn. These findings suggest that refining the N fertilization recommendation by accounting for soil N supplied by earthworms could potentially reduce fertilizer costs and environmental N losses.     

Bulk density as a soil quality indicator during conversion to no-tillage

Producers often identify compaction as an important problem, so bulk density is usually included in minimum data sets used to evaluate tillage and crop management effects on soil quality. The hypothesis for this study was that bulk density and associated water content would be useful soil quality indicators for evaluating the transitional effects associated with changing tillage and crop management practices on deep-loess soils. The study was conducted on three deep-loess, field-scale watersheds located in western Iowa, USA. The soils are classified as Haplic Phaeozems, Cumulic-Haplic Phaeozems, and Calcaric Regosols. Watersheds 1 and 2 were converted in 1996 from conventional tillage to no-tillage, while watershed 3 was maintained using ridge-tillage and continuous corn (Zea mays L.), a practice implemented in 1972. Watershed 1 was converted to a corn—soybean (Glycine max (L.) Merr.) rotation while watershed 2 was converted to a 6-year rotation that included corn, soybean, corn plus 3 years of alfalfa (Medicago sativa L.). Bulk density and water content were measured at three landscape positions (summit, side-slope, and toe-slope), in 20 mm increments to a depth of 300 mm, five times between September 1996 and May 2000. Organic C and total N were also measured to a depth of 160 mm during the initial sampling. Neither bulk density nor water content showed any significant differences between the two watersheds being converted to no-tillage or between them and the ridge-till watershed. There also were no significant differences among landscape positions. Bulk densities and water contents showed some differences when adjacent sampling dates were compared, but there was no overall or consistent trend. Our results show that bulk density is not a useful soil quality indicator for these soils within the bulk density range encountered (0.8–1.6 Mg m³). Our results also confirm that producers do not necessarily have to worry about increased compaction when using ridge-tillage or changing from conventional to no-tillage practices on these or similar deep-loess soils.     

Corn Yield and Nitrogen- and Water-Use under No-Tillage Rotations

Increased crop diversity and length of rotation may improve corn (Zea mays L.) yield and water- and nitrogen-use efficiency (WUE and NUE). The objectives of this study were to determine effects of crop rotation on corn yield, water use, and nitrogen (N) use. No-tillage (NT) crop rotations were started in 1997 on a Barnes clay loam (fine-loamy, mixed, superactive, frigid Calcic Hapludoll) near Brookings, S.D. Rotations were continuous corn (CC), corn–soybean [Glycine max (L.) Merr.] (CS), a 3-year rotation of corn–soybean–oat/pea (Avena sativa L. and Pisum sativum L.) hay (CSH), a 3-year rotation of corn–soybean–spring wheat (Triticum aestivum L.) (CSW), and a 5-year rotation of corn–soybean–oat/pea hay companion seeded with alfalfa (Medicago sativa L.)–alfalfa–alfalfa (CSHAA). Fertilizer N was applied to corn on all rotations at planting (16 kg N ha^?1) and side-dressed (64 kg N ha^?1). Average corn grain yields (1998–2007) were greatest under CSW (7.38 Mg ha^?1) and least under CC (4.66 Mg ha^?1). Yields were not different among CSH, CSW, and CSHAA rotations. Water-use efficiency of rotation was ordered as CSW > CSH > CSHAA > CS > CC. Nitrogen-use efficiency was greatest under CSW and least under CC. There were no differences in yield advantage (YA) among crop rotations during years with plentiful early-season rainfall (May 1–July 31). In years with low spring rainfall, YA was greatest under CSW (54%) and least under CSHAA (33%). Corn yields under extended rotations (CSH, CSW, and CSHAA) were greater than under CC and CS, but lack of rainfall may result in reduced yields under CSHAA.     

Performance Evaluation of Integrated Constructed Wetlands Treating Domestic Wastewater

The performances of a new and a mature integrated constructed wetland (ICW) system treating domestic wastewater were evaluated for the first time. The new ICW in Glaslough (near Monaghan, Ireland) comprises five wetland cells, and the mature system in Dunhill (near Waterford, Ireland) comprises four cells. The performance assessment for these systems is based on physical and chemical parameters collected for 1 year in Glaslough and 5 years in Dunhill. The removal efficiencies for the former system were relatively good if compared to the international literature: biochemical oxygen demand (BOD, 99.4%), chemical oxygen demand (COD, 97.0%), suspended solids (SS, 99.5%), ammonia nitrogen (99.0%), nitrate nitrogen (93.5%), and molybdate-reactive phosphorus (MRP, 99.2%). However, the mature ICW had removal efficiencies that decreased over time as the Dunhill village expanded rapidly. The mean removal efficiencies were as follows: BOD (95.2%), COD (89.1%), SS (97.2%), ammonia nitrogen (58.2%), nitrate nitrogen (?11.8%), and MRP (34.0%). The findings indicate that ICW are efficient in removing BOD, COD, SS, and ammonia nitrogen from domestic wastewater. Moreover, both ICW systems did not pollute the receiving surface waters and the groundwater.     

Innovative Technology of COD and BOD Reduction from Coffee Processing Wastewater Using Avocado Seed Carbon (ASC)

The study estimated the efficiency of Avocado seed carbon (ASC) for chemical oxygen demand (COD) and biochemical oxygen demand (BOD) reduction from coffee processing wastewater. It was performed under batch mode conditions to investigate the optimum operating conditions and efficiency for COD and BOD reduction with ASC compared with commercial activated carbon (CAC). Adsorption isotherm study was also performed and it was found that the values of regression coefficient (r ²), adsorption capacity (k), and adsorption intensity (1/n) for COD and BOD reduction with ASC were comparable to those of CAC. Under optimum operating conditions, the maximum percentage reduction of COD and BOD concentration using ASC was 98.28% and 99.19%, respectively and with CAC was 99.12% and 99.45%, respectively and hence adsorption capacity of ASC is comparable with that of CAC. Thus, this technique may be a good option for treatment of domestic wastewater.     

Crop management effects on soil carbon sequestration on selected farmers’ fields in northeastern Ohio

Soil organic carbon (SOC) pool is the largest among terrestrial pools. The restoration of SOC pool in arable lands represents a potential sink for atmospheric CO₂. Restorative management of SOC includes using organic manures, adopting legume-based crop rotations, and converting plow till to a conservation till system. A field study was conducted to analyze soil properties on two farms located in Geauga and Stark Counties in northeastern Ohio, USA. Soil bulk density decreased with increase in SOC pool for a wide range of management systems. In comparison with wooded control, agricultural fields had a lower SOC pool in the 0–30 cm depth. In Geauga County, the SOC pool decreased by 34% in alfalfa (Medicago sativa L.) grown in a complex rotation with manuring and 51% in unmanured continuous corn (Zea mays L.). In Stark County, the SOC pool decreased by 32% in a field systematically amended with poultry manure and 40% in the field receiving only chemical fertilizers. In comparison with continuous corn, the rate of SOC sequestration in Geauga County was 379 kg C ha⁻¹ year⁻¹ in no-till corn (2 years) previously in hay (12 years), 760 kg C ha⁻¹ year⁻¹ in a complex crop rotation receiving manure and chemical fertilizers, and 355 kg C ha⁻¹ year⁻¹ without manuring. The rate of SOC sequestration was 392 kg C ha⁻¹ year⁻¹ on manured field in Stark County.     

Short-term effect of tillage and crop rotation on microbial community structure and enzyme activities of a clay loam soil

A field study was carried out to analyze the short-term (2 years) effect of tillage and crop rotation on microbial community structure and enzyme activities of a clay loam soil. The experimental design was a split-plot arrangement of treatments, consisting of two tillage treatments—ridge tillage (RT) and no-tillage (NT)—in combination with two crop rotation treatments—corn (Zea mays L.) monoculture and a 2-year corn-soybean (Glycine max L.) rotation. Phospholipid fatty acid (PLFA) profiles were used to assess soil microbial community structure. No-tillage resulted in significantly higher total PLFAs compared to the RT treatment, which was accompanied by higher activities of protease, β-glucosaminidase, and β-glucosidase. This suggests a close link between soil microbial communities and enzyme activities in response to tillage. The increase of total microbial lipid biomass in the NT soils was due to the increase in both fungal and bacterial PLFAs. Crop rotation had little effect on soil bacterial communities and enzyme activities, but it significantly influenced soil fungal communities, particularly arbuscular mycorrhizal fungi. Soils under monoculture corn had higher fungal biomass than soils under corn-soybean rotation regardless of tillage treatment.     

Surface and Subsurface Phosphorus Losses from Sugarcane Fields with Different Management Practices

Phosphorus losses in runoff from sugarcane fields can contribute to non-point source pollution of surface and subsurface waters. The objective of this study was to evaluate the effects of three different management practices on P losses in surface runoff and subsurface leaching from sugarcane (Saccharum officinarum L.) fields. Field experiments with treatments including conventional burning (CB), compost application with burning (COMB), and remaining green cane trash blanketing (GCTB) treatments were carried out to assess these management practice effects on P losses from sugarcane fields. In the CB treatment, sugarcane residue was burned after harvest. The COMB treatment consisted of compost applied at ??off bar?? with sugarcane residue burned immediately after harvest. Compost was applied in the amount of 13.4 Mg ha^?1 annually, 8 weeks before planting. In the GCTB treatment, sugarcane residue was raked off from the row tops and remained in the wheel furrow after harvest. Surface runoff was collected with automatic refrigerated samplers, and subsurface leachate was collected with pan lysimeters over a period of 3 years. Measured concentrations of total P (TP), dissolved reactive P (DRP), and particulate P (PP) in surface runoff from the COMB treatment were significantly higher than concentrations from the CB and GCTB treatments. The mean losses of P (TP and DRP) after burning (postharvest, years 2 and 3) were significantly greater than the no-burn treatment (preharvest, year 1) in the CB, COMB, and CB/COMB/GCTB combined options. Additionally, the mean losses of total suspended solid and total combustible solids in residue burning were, on average, 2.7 and 2.2 times higher than the no-burn practices, respectively (preharvest and GCTB treatment). Annual P losses from surface runoff in the third year of study were 12.90%, 6.86%, and 10.23% of applied P in CB, COMB, and GCTB treatments, respectively. However, the percent of annual DRP losses from applied P in COMB and GCTB treatments was similar magnitude, and their values were less than 50% compared to the value from CB treatment. In the leaching study, percent of monthly mean TP and DRP losses in the COMB and GCTB treatments were greatly reduced. Based on these results, the COMB and GCTB procedures were equally recommended as sugarcane management practices that improve water quality in both surface runoff and subsurface leachate.     

Sediment and Nutrient Losses from Field-Scale Cropland Plots Treated With Animal Manure and Inorganic Fertilizer

A field-scale plot study was conducted at Virginia Tech's Prices Fork Research Farm, to evaluate the transport of nutrients in runoff from manure and fertilizer applied at P-based agronomic rates to cropland planted to corn. Simulated rainfall events representing 2- to 10-year storms in southwest Virginia, occurring 1 and 2 days following manure and fertilizer application were used to generate runoff. Plots were treated with surface applied poultry litter, surface applied and incorporated dairy manure, incorporated inorganic fertilizer, and no fertilizer (control). Application rates were based upon agronomic phosphorus (P) requirements of corn. The concentration of total suspended solids and nutrients decreased from the first to the second simulated rainfall event; however, the edge-of-field mass loss or yield increased due to increased runoff volume. Surface application of dairy manure resulted in 25–50% lower runoff volumes and 35–60% lower total suspended solid yields when compared to surface applied poultry litter. Surface applied poultry litter produced the greatest total P and dissolved reactive P losses. Results of this study suggest that manure applied based on crop P requirements can still yield significant edge-of-field nutrient losses, if rainfall occurs soon after application.     

Residual effects of potassium placement for conservation-till corn on subsequent no-till soybean

Biannual surface application of potassium (K) fertilizer prior to corn (Zea mays L.) in a corn–soybean (Glycine max (L.) Merr.) rotation has been common in conventional-till crop production in North America; however, whether this traditional K management practice is effective for soybean when both corn and soybean are grown with conservation tillage is largely unknown. This study evaluated the residual effects of spring K fertilizer placement in conservation tillage systems applied to previous corn on subsequent no-till soybean. Experiments involving a corn–soybean rotation were conducted from 1997 to 2000 on a silt loam soil (Albic Luvisol) with 12 years of continuous no-till management near Paris, Ontario, Canada. The fields had low initial soil-test K levels (<61 mg l⁻¹) and evident soil K stratification in the top 20 cm. In the “corn” years from 1997 through 1999, spring K fertilizer placement methods of deep band (76 cm centers), surface broadcast, broadcast plus shallow band, and no K were evaluated for no-till, spring zone-till, and spring mulch-till tillage systems (1997 and 1998) but for no-till alone in 1999. From 1998 to 2000, soybean was no-till planted in 19 cm row widths on the respective previous-year corn treatments without further K fertilizer application. Soybean leaf K concentrations responded more frequently and positively to K application in no-till corn than in zone-till and mulch-till corn. Deep band and surface broadcast K placements were similar in their residual effects on soybean leaf K. Positive soybean yield responses to residual K fertilizer were observed in only 1 out of 3 years despite consistent increases in both soil K and soybean leaf K concentrations where K was applied to previous corn. On long-term no-till fields with low soil K levels, interrupting a continuous no-till corn–soybean system with mulch-till corn production provided residual benefits in soil K availability and leaf K nutrition for subsequent no-till soybean. Furthermore, the residual effects of K fertilizer applied to previous corn on subsequent no-till soybean were not affected by K placement method.