Manure Application Timing Research Articles

Is green manure a viable substitute for inorganic fertilizer to improve grain yields and advance carbon neutrality in paddy agriculture?

Green manure is a widely applied to increase grain yield, while it also attributes to greenhouse gas (GHG) emissions in agriculture ecosystems. Combining green manure with inorganic fertilizer inputs is a common practice that can influence soil GHG emissions and grain yield, however, its impacts on grain yield and global warming potential (GWP) under different initial soil conditions before rotating experiments and agronomic management in paddy fields remain unclear. We synthesized 508 data pairs to evaluate the responses of CO2 emissions, CH4 emissions, N2O emissions, and grain yield to combined inputs of green manure plus inorganic fertilizer compared with only inorganic fertilizer application. Our findings indicate that both inorganic fertilizer plus extra green manure (GM-E) and green manure substitutes for inorganic fertilizer (GM-S) could increase CO2 emissions (22.5 %−76.8 %), CH4 emissions (100 %−103 %), N2O emissions (29.8 %−50.9 %), and yield (2.21 %−19.6 %). Except for GM-E, which showed a non-significant increase in grain yield. The initial soil properties before rotating experiments, the types and timing of green manure application were key drivers of GHG emissions and yield, and extra green manure applied in areas with low initial soil pH and high C:N can increase GWP and yield. Overall, the mixed green manure application had greater impact than leguminous or non-leguminous green manure applied alone. The responses of GHG emissions and yield to GM-S were modulated by mean annual precipitation and initial soil properties before rotating experiments, and green manure substitutes for inorganic fertilizer in areas with high initial soil pH and low C:N can increase GWP and yield. Meanwhile, excessive precipitation caused a reduction in yield and a significant increase in GWP intensity. Our results showed that extra green manure applications of less than 68.1 kg N ha−1 would not significantly increase GWP. Therefore, an effective green manure strategy can achieve a win-win situation for the dual challenge of agricultural production and climate change mitigation.

Post Manure Application Time and Rate on Soil Nutrient Changes and Seed Proximate Contents of Egusi Melon (Colocynthis citrullus L.)

ABSTRACT The efficiency of manure application is a function of quantity and time of application. Two field trials were conducted to determine the effects of time and quantity of manure application on soil nutrient dynamics and proximate contents in Abeokuta, Nigeria, by cultivating egusi melon with 0, 5, 10, and 15 t.ha−1 poultry manure (PM) applied at 2 and 4 weeks before planting (WBP). Melon was planted at 2 and 4 weeks after manure application (WAMA). The year of cultivation affected post cropping soil nutrient contents. Soil organic matter was not reduced with 10 t.ha−1 application. It also maintained soil nitrogen content and increased exchangeable potassium. Soil calcium and magnesium content increased with cropping. In 2017, planting with 5 t.ha−1 PM applied at 2 WBP gave the highest exchangeable acidity content, but from 10 t.ha−1 PM applied at 4 WBP, in 2018. Soil calcium and magnesium contents were higher with 2 years cropping. It was highest with either 10 t.ha−1 PM at 2 WBP or 5 t.ha−1 PM at 4 WBP. Soil magnesium content was highest with 10 t.ha−1 PM at 2 WBP. Cropping increased soil sand and clay particles but reduced silt particles. Seed crude protein was reduced with 2 years cropping. It was highest from 15 t.ha−1 PM applied at 2 WBP in 2017. Seed fat and carbohydrate contents were increased with 2 years cropping. For soil calcium and magnesium contents, 10 t.ha−1 PM applied at 2 WBP poultry manure is optimum.

Effects of manure application timing on rice water productivity, nutrient leaching, and runoff under monsoon climate

Effects of manure application timing on rice water productivity, nutrient leaching, and runoff under monsoon climate

Water quality benefits of weather-based manure application timing and manure placement strategies

The timing of manure application and placement of manure significantly affects manure nutrient use efficiency and the amount of nutrient lost from a field. Application of manure prior to a minimal precipitation period, and manure application through incorporation, reduces risks associated with nutrient loss through surface runoff. The current study aims to explore potential water quality impacts related to manure application strategies on the timing of application and approach (surface broadcasting or incorporation). The Soil and Water Assessment Tool (SWAT) was used to represent manure application scenarios and quantify potential water quality impacts in Susquehanna River Basin located in the Mid-Atlantic region of the United States. A baseline (business-as-usual) scenario was developed with manure application based on crop planting date and manure storage availability, and surface broadcasting as the application approach. The baseline was compared with a strategically timed manure application considering weather forecasting and manure incorporation. The strategic, weather-based manure application approach reduced TN and TP loading at the outlet by 4% and 6%, respectively. Manure incorporation simulations considering low-disturbance injection showed significant reduction of about 19% for TN and 44% for TP at the watershed outlet. Winter closure of manure application could reduce organic nutrient loss. Winter application of manure in 21% of row cropped areas (2% of whole watershed area) increased organic N and P loading by 10% and 4%, respectively, at watershed outlet.

GROWTH AND DEVELOPMENT OF POTATO PLANTS DEPENDING ON THE TERMS OF APPLICATION OF MANUR

Potatoes are one of the most important agricultural crops in Kazakhstan. It is an indispensable food item, because it is popularly called a second bread for its nutritional value. The studies were conducted to identify the influence of the timing of litter manure application in conjunction with mineral fertilizers and planting density on the duration of potato development phases and plant height in the West Kazakhstan region. The experiments were laid by a systematic method with a tiered arrangement of variants in the experiment, the repetition is 3-fold. Cattle manure was used on a straw litter of autumn-winter harvesting. The following types of fertilizers were used: ammonium nitrate, double superphosphate, potassium chloride. Research methods: descriptive method and methods of field experiments. Statistical processing of the yield was carried out by a dispersion analysis. Phenological observations in experiments have shown that the doses of mineral fertilizers and the timing of manure application have some effect on the phases of potato plant development. Weather conditions also have a great influence on the duration of interphase periods. The timing of manure application in combination with mineral fertilizers had a certain effect on plant growth, but differences in plant height were more noticeable from the budding phase and in subsequent phases, therefore, we provide data on plant height in the flowering phase. The plant height was also influenced by the timing of manure application, and the weather conditions of the year, as well as the density of planting, the lowest plants were obtained in variants without manure application and its application in winter on snow. This pattern has been observed in all years of research. The tallest plants are noted when applying manure under the chill and during spring application. This work is of practical importance for the cultivation of potatoes on dark chestnut soils of the Republic of Kazakhstan under irrigation with the use of optimal doses of mineral fertilizers and manure. Properly chosen doses of mineral fertilizers and manure can increase the yield of potatoes from 35% to 50%, while now it is 75-80 centners per hectare

THE PHENOLOGY, GROWTH AND DEVELOPMENT OF POTATO PLANTS DEPENDING ON THE TIMING OF MANURE APPLICATION

The studies were conducted to identify the influence of the timing of litter manure application in conjunction with mineral fertilizers and planting density on the duration of potato development phases and plant height. The experiments were laid by a systematic method with a tiered arrangement of variants in the experiment, the repetition is 3-fold. Research methods: descriptive method and methods of field experiments. Phenological observations in experiments have shown that the doses of mineral fertilizers and the timing of manure application have some effect on the phases of potato plant development and plant growth. The lowest plants were obtained in variants without manure application and its application in winter on snow. The tallest plants are noted when applying manure under the chill and during spring application. This work is of practical importance for the cultivation of potatoes on dark chestnut soils of the Republic of Kazakhstan under irrigation with the use of optimal doses of mineral fertilizers and manure.

Manure Application Timing and Incorporation Effects on Ammonia and Greenhouse Gas Emissions in Corn

Manure application influences ammonia (NH3) and greenhouse gas emissions; however, few studies have quantified the effects of manure application methods and timing on NH3, nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) fluxes simultaneously. We evaluated surface-applied liquid manure application with disk incorporation versus injection on NH3, N2O, CO2, and CH4 fluxes in central Wisconsin corn silage (Zea mays L.) plots during pre-plant (PP) and sidedress (SD) application windows from 2009 to 2011. Manure treatments were PP injection (PP-Inject) and injection at sidedress time (SD-Inject) to growing corn, along with two incorporation times for PP surface application (within 24 h—PP-1-hr; within 3 days—PP-3-day). Mean NH3 emissions were 95% lower for injected treatments compared to surface application in both years, with larger losses for PP-3-day and SD-Surf. While N2O fluxes were generally low, larger increases after manure application were associated with injection and triggered by soil moisture/temperature changes. Mean CO2 and CH4 were unaffected by manure treatments and influenced more by weather. Overall, injection conserved more available soil N while contributing to modest N2O emission, suggesting manure injection may offer greater agri-environmental benefits on the whole over surface application.

Using remote sensing to identify liquid manure applications in eastern North Carolina

Nutrient pollution from farm fertilizers and manure is a global concern. Excess nitrogen and phosphorous has been linked to algal blooms and a host of other water quality issues. In the U.S., most animal production occurs in concentrated animal feeding operations (CAFOs) housing a significant number of animals in a confined space. CAFOs tend to cluster in space and thus generate large quantities of manures within a small area. Liquid manure from CAFOs is often stored in open-air lagoons and then applied via irrigation to crops on nearby ‘sprayfields’. The full scope and extent of CAFO impacts remain unclear because of the paucity of public information regarding animal numbers, barn and lagoon locations, and manure management practices. Where and when manure is applied on the landscape is key missing data that is needed to better understand and mitigate consequences of CAFO management practices. The aim of this study was to detect land applications of liquid manure using a remote sensing approach. We used random forest models incorporating C-Band synthetic-aperture radar, multispectral imagery, and other predictors to examine soil moisture conditions indicating probable liquid manure applications across known sprayfields in eastern North Carolina. Our models successfully distinguished saturated and unsaturated soils within corn, soybean, grassland, and ‘other’ crops, with 93–98% accuracy against validation for clear weather periods during the dormant, early, and late growing seasons. A Kruskal-Wallis test revealed that the mean soil saturation frequency was significantly higher on sprayfields than non-sprayfields of the same crop type (p < 2.2e-16). We also found that manure applications were concentrated within ∼1 km from the point of generation. This is the first application of satellite-based radar for identifying the location and timing of manure applications over broad areas. Future work can build on these methods to further understand manure management at CAFOs, as well as to improve pollution source tracking and modeling.

Pertumbuhan dan Hasil Padi Sawah Organik pada Berbagai Jenis dan Waktu Aplikasi Pupuk Hijau Legum Tahunan

Abstract— Green manure is a source of soil organic matter and nutrients for organic lowland rice, especially nitrogen. The use of various species of perennial legume green manure as a source of nitrogen that the right application time is not widely reported. The research objectives are to examine the effect of the interaction of application time of several species of perennial legume green manure on physiological characteristics, growth and yield of organic lowland rice, and to find the right application time of several species of perennial legume green manure to support growth and organic rice yields. We used a factorial RCBD, consisting of two factors and three groups, and control. The first factor is the species of perennial legume green manure, consisting of four species, namely: Turi, Gliricidia, Lamtoro, and Cow Manure. The second factor is the time of application of perennial legume green manure, consisting of three levels, namely: 4 weeks before planting rice seeds, 2 weeks before planting rice seeds, and at the same time planting rice seeds. The results showed that the growth and yield of organic lowland rice was influenced by the species and timing of perennial legume green manure application. The optimal application time to Turi leaves is 1.06 weeks before planting rice seeds with grain yield 9.29 t/ha, the optimal application time to Gliricidia leaves is 1.85 weeks before planting with grain yield 10.24 t/ha, and the optimal application time Lamtoro leaves is 2.58 weeks before planting with grain yield of 9.78 t/ha.

Knowledge and Association of Solar Pump Users Regarding Vegetable Production Technology in Jaipur Rajasthan

Rajasthan has outstanding solar radiation in India and a solar water pump is a great investment that makes money in the long run. The present study was conducted in Jaipur district with 120 beneficiary and non- beneficiary farmers regarding knowledge about the improved practices of vegetable production possessed by solar pump users during 2020. The practices namely- selection of improved seed variety, time of sowing, seed treatment, organic and chemical manure application of irrigation at the right time, intercultural operations, weed management, insect and disease management etc. were found as popular practices. The results of the study revealed that majority (95%) of beneficiary fall into the category of medium to high level of knowledge against 80 per cent of the non-beneficiary were falling under low to medium knowledge level. It can be summarized that the variables viz., education, occupation, annual family income, size of land holding, farm mechanization, utilization of information, contact with extension agents etc. were found significant with their knowledge of vegetable production technology. The results also depicted that age was found in non-significant relationship with knowledge of vegetable production technology. There was a significant association between knowledge of vegetable production technology of non-beneficiaries with their occupation, size of land holding and contact with extension agents. In case of age no association was found between age and knowledge of vegetable production technology for both the beneficiary and non-beneficiary farmers.

Water Quality Benefits of Weather-Based Manure Application Timing and Manure Placement Strategie

Water Quality Benefits of Weather-Based Manure Application Timing and Manure Placement Strategie

The Effect of the Timing of Manure Application in Combination with Mineral Fertilizers and Planting Density on the Weediness of Potato Plantings

Potatoes are one of the most responsive crops for grooming techniques since in the period from seedlings before closing rows are easily suppressed by weeds that take away nutrients, water, light from it. The factor that causes high harm to potatoes is weed. By absorbing a large number of nutrients and moisture from the soil, weeds inhibit the growth and development of plants, reducing their potential productivity. The purpose of the study was to establish the effect of the timing of the introduction of bedding manure in conjunction with mineral fertilizers and planting density on the weediness of potato plantings. Studies were provided to identify the impact of the timing of bedding manure together with mineral fertilizers and planting density for weed planting potatoes. Experiments were laid by the systematic method with a tiered arrangement of variants in the experiment with a 3-fold repetition. We used cattle manure on straw bedding for autumn-winter harvesting. The following types of fertilizers were used: ammonium nitrate, double superphosphate, potassium chloride. Determination of the amount and biomass of weeds in potato plantings was carried out in the flowering phase and before harvesting. The application of manure was accompanied by an increase in the number and weight of weeds. Annual weeds predominated in potato plantings: Amaranthus retroflexus L., 1753 and Amaranthus blitoides S. Watson, 1877, Chenopodium album L. Chenopodium album L., 1753, Setaria P. Beauv, 1812 and Setaria viridis (L.) P. Beauv, 1812, Echinochloa crus-galli (L.) BEAUV., 1812 and others, perennials included Cirsium arvense (L.) SCOP. 1772 and Sonchus arvensis L., 1753, (Elytrigia repens (L.) DESV. ex NEVSKI, 1933 and others. Planting density also has a definite effect on the development of weeds. When manure was applied in autumn under the plow, the number of weeds increased in comparison with other options, where only mineral fertilizers were applied. The application of manure over frozen plow and in winter over snow leads to a slight decrease (2.3-2.5 pcs/m2) of weeds. The greatest number of weeds is observed during the spring application of manure for plowing the fall plow. Nevertheless, studies aimed at clarifying the composition and structure of weediness, the number and weight of weeds in potato plantings are of great practical importance for local agricultural producers. These data should contribute to the development of an effective weed control system and high yields of potatoes in the region

Manure Application Timing and Tillage Influence on Nutrient Loss from Snowmelt Runoff

Winter manure application contributes substantial nutrient loss during snowmelt and influences water quality. The goal of this study is to develop best management practices (BMPs) for winter manure management. We compared nutrient concentrations in snowmelt runoff from three dates of feedlot solid beef manure application (November, January, and March) at 18 tons ha−1 on untilled and fall-tilled plots. The manure was applied at a single rate. Sixteen 4 m2 steel frames were installed in the fall to define individual plots. Treatments were randomly assigned so that each tillage area had two control plots, two that received manure during November, two in January, and two in March. Snowmelt runoff from each individual plot was collected in March and analyzed for runoff volume (RO), ammonium-nitrogen (NH4-N), nitrate-nitrogen (NO3-N), total suspended solids (TSS), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and total dissolved phosphorus (TDP). Snowmelt runoff concentrations and loads of NH4-N, TKN, TP, and TDP were significantly higher in runoff from manure application treatments compared to control. The concentration of NH4-N and loads of NH4-N and TDP were significantly (p = 0.05) greater (42%, 51%, and 47%, respectively) from untilled compared to fall-tilled plots. The November application significantly increased RO, NH4-N, and TDP concentrations and loads in the snowmelt runoff compared to January and March applications. Results showed that nutrient losses in snowmelt runoff were reduced from manure applications on snow compared to non-snow applications. The fall tillage before winter manure application decreased nutrient losses compared to untilled fields.

Early growth and dry matter partitioning of yellow passion fruit as affected by time of application and method of poultry manure placement

Purpose Passion fruit cultivation and utilization is fast emerging in Nigeria. Poultry farms are increasing with the corresponding increase in poultry manure production which is relatively affordable by farmers. Two experiments were conducted to evaluate the effect of placement method and time of poultry manure (PM) application on early growth and dry matter partitioning of yellow passion fruit. Method PM placement methods were incorporation, top-dressing, bottom-dressing and split combination of top-and bottom-dressing while time of PM application comprised application at transplanting, 2, 4 and 6 weeks after transplanting (WAT). The experiments were laid out as completely randomized design, replicated five and six times, respectively for PM placement methods and time of PM application. Growth and dry matter yield were determined at two weeks' interval and 20 WAT, respectively. Results Longest vines (78.5 cm) were significantly (p <0.05) produced by plants that were grown in PM incorporated medium. Thickest stems (6.75 mm), highest number of leaves (66.4) and dry matter accumulation were recorded in plants that received PM as top-dressing followed by PM incorporation. Application of PM at transplanting resulted in longest vines (95.8 cm), highest number of leaves (69.5) and dry matter partitioning to leaves, vines and roots. Conclusion PM top placement performed best with respect to early growth parameters and dry matter accumulation followed by PM incorporation, hence PM top placement is recommended for production of vigorous passion fruit vines in container. Poultry manure should be applied at transplanting for vigorous vines and not delayed beyond 4 weeks after transplanting.

Soil Organic Carbon Dynamics in Semi-Arid Irrigated Cropping Systems

Insufficient characterization of soil organic carbon (SOC) dynamics in semi-arid climates contributes uncertainty to SOC sequestration estimates. This study estimated changes in SOC (0–30 cm depth) due to variations in manure management, tillage regime, winter cover crop, and crop rotation in southern Idaho (USA). Empirical data were used to drive the Denitrification Decomposition (DNDC) model in a “default” and calibrated capacity and forecast SOC levels until 2050. Empirical data indicates: (i) no effect (p = 0.51) of winter triticale on SOC after 3 years; (ii) SOC accumulation (0.6 ± 0.5 Mg ha–1 year–1) under a rotation of corn-barley-alfalfax3 and no change (p = 0.905) in a rotation of wheat-potato-barley-sugarbeet; (iii) manure applied annually at rate 1X is not significantly different (p = 0.75) from biennial application at rate 2X; and (iv) no significant effect of manure application timing (p = 0.41, fall vs. spring). The DNDC model simulated empirical SOC and biomass C measurements adequately in a default capacity, yet specific issues were encountered. By 2050, model forecasting suggested: (i) triticale cover resulted in SOC accrual (0.05–0.27 Mg ha–1 year–1); (ii) when manure is applied, conventional tillage regimes are favored; and (iii) manure applied treatments accrue SOC suggesting a quadratic relationship (all R2 &gt; 0.85 and all p &lt; 0.0001), yet saturation behavior was not realized when extending the simulation to 2100. It is possible that under very large C inputs that C sequestration is favored by DNDC which may influence “NetZero” C initiatives.

Effect on forage yield and nutrient uptake of long-term surface application of manure at various rates and times in the growing season to timothy grown on two contrasting soils

Although much of the manure in Canada is surface-applied to forages, little research exists evaluating time of year (Time) and rate (Rate) of application on forage yield and nutrient uptake. Field trials (10 yr) on two soils (sandy loam upland and silty clay loam dykeland) investigated this. Experimental arrangement was a factorial [Time (spring, summer, early, and late fall manure applications)] plus a control [spring-applied ammonium nitrate fertilizer (ANF)] in a Latinized split plot. ANF at 0, 25, 50, 100 and 200 kg N·ha−1; 0, 75, 150, and 300 as semi-solid beef (SSM) and 150 kg N·ha−1 as liquid dairy manure (LDM), constituted respective splits. The Time × Rate interaction, later in the trial on the upland soil, showed higher yields and nutrient uptakes with fall manure application. There was little interaction on the dykeland soil; summer application resulted in higher yields at times. For both soils, the optimal long-term application rate of SSM was approximately 150 kg N·ha−1 while that of ANF was approximately 100 kg N·ha−1. Inherent fertility of dykelands resulted in lesser responses to manure addition. Negligible and significant residual N occurred with fertilizer and manure, respectively. Nitrogen, phosphorus, potassium, calcium, magnesium, manganese, copper, zinc, and boron uptakes were due to amendment impact on yield. The recommended rate is 150 kg N·ha−1 of SSM or LDM applied in fall and summer to Maritime grasslands grown on upland and dykeland soils, respectively. Yield differences may not warrant producers adjusting timing of in-season manure application.

Nitrogen dynamics in grain cropping systems integrating multiple ecologically based management strategies

AbstractNitrogen (N) management is a critical agronomic challenge, as N losses are a source of pollution affecting both waterways and air quality and a potential economic loss for farmers. One approach to N conservation is through ecologically based agricultural systems that reduce tillage and incorporate cover crops. However, these systems exhibit considerable complexity resulting in potential agronomic trade‐offs. To address these concerns, four crop management systems were implemented within an organically managed corn–soy–winter grain crop rotation. These systems varied in tillage frequency and intensity, cover crop species selection, cover crop termination and establishment methods, fertilizer management, and cash crop season length. We used field measurements to investigate the impact of each system on N pools and to reveal the strengths and weaknesses of each system in addressing N provisioning services, with a focus on the supply and retention of N before and after the corn phase of the rotation. All systems had greater estimated N inputs (via manure and N‐fixation) than outputs (via crop harvest) at the end of the three‐year rotation, demonstrating the importance of prioritizing N retention in cover crops. Interactions among system components were important drivers of temporal N dynamics; cover crop species traits and timing of manure application contributed to differences in total aboveground plant biomass N among systems. For example, one cropping system which included a no‐till corn planting into a rolled cover crop mulch had soil inorganic N availability that was asynchronous with the N needs of the corn crop even though it received the same amount of N inputs as the other systems. In general, neither interseeding cover crop mixtures nor reducing tillage resulted in marked N benefits at the system level; we did not observe improved N retention from either practice in these systems, and there was no increase in N uptake by corn. What did clearly emerge from this experiment is the importance of managing for synchrony between soil inorganic N availability and cash crop N demand as influenced by the N retention capacity of cover crops and the timing of N mineralization due to tillage.

Improving vegetable production under semi-arid, saline conditions in south-western Madagascar

AbstractAgricultural production on the Mahafaly Plateau in SW-Madagascar has traditionally been based on subsistence rain-fed agriculture, with yields declining as a result of low soil fertility, recurrent droughts, and erratic rainfall. Market-oriented vegetable production in this area may help households improve their nutrition and diversify their income. In field trials between the 2013 and 2016 dry cropping seasons, the feasibility of carrot (Daucus carota L.) and onion (Allium cepa L.) production was assessed by testing effects of manure and charcoal amendments, shading, and seed quality on yields. Due to damage caused by cyclones and strong winds, only data from 2013 and 2016 are reported in this paper. Additionally to the field experiments, effects of salinity on seed germination were also examined under laboratory conditions and in the field. Carrot dry matter (DM) yields were 0.24 to 2.76 t·ha−1 while those of onion were 0.15 to 0.99 t·ha−1 DM. While the combination of manure and charcoal application had only minor effects on crop growth, manure alone increased carrot yield by 26% across years. After one cropping season, manure application reduced soil pH from 9.0 to 8.6 and increased soil Corg from 0.87 to 1.76%, N from 0.08 to 0.14%, and P from 10.6 to 15.1 mg·kg−1. Shading reduced carrot yields from 0.87 to 0.58 t·ha−1 DM in 2013 and from 1.87 to 0.85 t·ha−1 DM in 2016, but increased onion yield in 2013 from 0.24 to 0.62 t·ha−1 DM. Carrot seed procured locally performed better in the field than seed imported from the capital which translated into differences in seedling emergence. Saline irrigation water (electrical conductivity = 7.03 mS·cm−1) reduced seedling emergence rate of carrot from 73 to 20% and for onion from 44 to 28% and unprimed seeds performed better than primed ones. Using shading during the dry season is not advisable for carrot and onion production, but improving seed quality and targeted use of soil amendments (time of manure application, manure quality) may enhance vegetable yields.

Short Term Effects of Livestock Manures on Soil Structure Stability, Runoff and Soil Erosion in Semi-Arid Soils under Simulated Rainfall

The long term effects of applying livestock manures as soil amendment are well known. However, these manures usually contain high soluble salts content, which could increase the soil salinity and sodicity within a short time after their application. The aim of this study was to investigate the short term effects of animal manure application on soil structure stability, infiltration rate (IR), and runoff and soil erosion formation under rainfall conditions. Two soils, a non-calcareous, sandy soil with 0.2% organic matter, and a calcareous, clayey soil with 4.7% organic matter were sampled from a semiarid region. The soils were mixed with raw cattle manure or with compost, and soils with no addition were considered as a control. The two soils with the three treatments were incubated for 21 days, and then subjected to 80 mm of simulated rainstorm. In contradiction to previous works, it was found that the manure reduced soil structure stability, reduced infiltration, increased surface runoff and led to soil loss. The negative impact of the raw manure on soil structure was stronger than that of the mature compost. The findings of this study indicate the high sensitivity of arable soils to erosion processes during the first few weeks following the addition of manure to the soil, and therefore could contribute to the decision-making process of the timing of manure application, namely to make sure that the manure is applied well before the rainy season, in order to avoid the aforementioned soil erosion.

Addressing the spatial disconnect between national-scale total maximum daily loads and localized land management decisions.

Regulatory watershed mitigation programs typically emphasize widespread adoption of best management practices (BMPs) to meet total maximum daily load (TMDL) goals. To comply with the Chesapeake Bay TMDL, jurisdictions must develop watershed implementation plans (WIPs) to determine the number and type of BMPs to implement. However, the spatial resolution of the bay‐level model used to determine these load reduction goals is so coarse that the regulatory plan cannot consider heterogeneity in local conditions, which affects BMP effectiveness. Using the Topo‐SWAT modification of the Soil and Water Assessment Tool (SWAT), we simulated two BMP adoption scenarios in the Spring Creek watershed in central Pennsylvania to determine if leveraging fine‐scale spatial heterogeneity to place BMPs could achieve the same (or better) nutrient and sediment reduction at a lower cost than the state‐level WIP BMP adoption recommendations. Topo‐SWAT was initialized with detailed land use and management practice information, systematically calibrated, and validated against 12 yr of observed data. After determining individual BMP cost effectiveness, results were ranked to design a cost‐effective BMP adoption scenario that achieved equal or greater load reduction as the WIP scenario for 74% of the cost using eight management‐based BMPs: no‐till, manure injection, cover cropping, riparian buffers, land retirement, manure application timing, wetland restoration, and nitrogen management (15% less N input). Because watersheds of this size typically represent the smallest modeling unit in the Chesapeake Bay Model, results demonstrate the potential to use watershed models with finer inference scales to improve recommendations for BMP implementation under the Chesapeake Bay TMDL.