Runoff Loss Research Articles

Reducing nutrient and sediment losses in surface runoff by selecting cattle supplement feeding areas based on soil type in New Zealand hill country

ABSTRACT Nutrient loss in surface runoff from hill country catchments is typically generated from small areas and over short time periods. This study compared nutrient and sediment losses in surface runoff when cattle were fed winter hay supplement on two hill country sub-catchments (∼0.3 ha) with contrasting soil types (imperfectly-drained and well-drained soils). Runoff samples were collected during seven events (June-August). During this period, two herds of 16 pregnant, mixed aged Angus cows were supplemented with 2 kg DM. cow day−1 of hay in a defined feeding area within each sub-catchment. The imperfectly-drained soil measured 4.8 times the volume of surface runoff compared to the well-drained soil. As a result, the imperfectly-drained soil lost 2.5 times the amount of sediment, 6.3 and 5.1 times the amount of total phosphorus (TP) and dissolved reactive phosphorus respectively and 4.5 times the amount of total nitrogen (TN). Surface runoff losses of nitrate-N from the well-drained soil were undetectable over the study period. Whilst overall nutrient losses were low over the short study period (0.22 kg TP ha−1 and 0.68 kg TN ha−1), the results highlight the potential benefit of strategically placing cattle feed supplements on soils less prone to surface runoff to improve freshwater outcomes.

Comparison of mechanical vs. chemical weed control in sugar beet – Environmental effects: soil erosion, earthworms, CO2e-emissions

Chemical weed control is widely criticized because of its potential ecotoxicological risks. However, the environmental effects of mechanical weeding have not been studied yet. This study aims to evaluate the effects of hoeing, herbicide spraying and combined hoeing-spraying in sugar beet on soil erosion, earthworm abundance, and greenhouse gas (GHG) emissions. Field trials were carried out in Lower Saxony on five sugar beet fields from 2019 to 2021. Runoff and soil erosion were measured by means of rainfall simulation on 2-m2 subplots after weed control. The earthworm abundance was determined in autumn using formalin expulsion. The resources consumption and GHG emissions of each weeding strategy were estimated using KTBL and Biograce online tools. The earthworm abundance was not affected by weeding strategy in most cases. Cumulative runoff and soil loss were six and eight times lower after hoeing compared to herbicide spraying, but only if the soil was crusted before rainfall simulation; otherwise, weed control did not affect soil erosion. The GHG emissions for mechanical and combined mechanical-chemical weed control were higher by factor 2.5 and 1.7, respectively, as compared to the reference chemical weed control. Hence, hoeing is, though non-toxic and erosion-retarding, the weeding strategy with the highest carbon footprint.

Assessment of Runoff and Soil Loss Under Natural Vegetation Cover and Rainfall in a Semi-Arid Catchment, West Pokot County, Kenya

Soil erosion has become a major cause of land degradation with regrettable economic losses. It has affected livelihoods of many agro-pastoral communities in Arid and Semi-arid Lands (ASALs). There is need for continuous assessment of soil erosion in these areas in order to provide sufficient data on soil loss for soil resource management, conservation, and land use planning. The purpose of this study was to determine the rate of soil loss by water for soil conservation planning in West Pokot County, Kenya. Two adjacent fields with variable vegetation cover density were identified in a semi-arid catchment for runoff plot research. Vegetation cover on the fields was measured using the transect line-intercept survey method. Field 1 had 25–50% vegetation cover while field 2 had 50–75% vegetation cover. On each field, three identical erosion plots with dimensions 20 m along the slope and 10 m wide were constructed. Runoff and sediment from the plots were measured for fifteen rainfall-runoff events during the long rains season. Data was analysed using correlation analysis and linear regression methods. The results show that runoff production varied from 1.03% to 1.44% of total rain water. Soil loss from the plots was 120.3–155.5 g/ . Runoff-rainfall correlation analysis showed a significant positive relationship (r =0.9609, P<0.05%) with 92.33% variance in runoff production. Soil loss had significant positive relationship with runoff (r =0.9840, P<0.05%) with 96.83% variance in soil loss. The study found that runoff production and soil loss was slow in the field with dense vegetation cover. Studies project an increase in human and livestock populations in semi-arid areas. This points at possible decrease in vegetation cover and increase in the rate of soil loss by water. The study recommends development of a soil conservation and management strategy in the study area.

Alternate freezing and thawing enhanced the sediment and nutrient runoff loss in the restored soil of the alpine mining area

Alternate freezing and thawing enhanced the sediment and nutrient runoff loss in the restored soil of the alpine mining area

Soil and Water Conservation Techniques in Tropical and Subtropical Asia: A Review

Soil and water loss is a severe environmental problem in tropical and subtropical Asia (TSA). This review systematically summarizes the techniques that have been widely applied in the TSA region and compares the conservation efficiency of these techniques based on the runoff and sediment reduction ratios (ηr and ηs). The results show that the current techniques can be divided into biological, engineering and agricultural practice measures, and in most cases, their efficiencies in reducing sediment loss (ηs = 14.0–99.5%, 61.3–100.0% and 0.6–95.4%, respectively) were higher than in reducing runoff loss (ηr = 2.8–9.38%, 0.28–83.3% and 1.62–70.2%, respectively). Monocultures of single tree species (e.g., Pinus massoniana) sometimes showed very limited conservation effects. Vetiver and alfalfa were more effective at reducing soil loss than other hedgerow species. Contour tillage, ridge farming, and reduced tillage generally showed high efficiencies in reducing soil loss compared with other agricultural practice measures. The combination of engineering and biological techniques could more effectively reduce soil and water loss compared with the application of these techniques along. Future works should be conducted to build unified technical standards and reasonable comprehensive evaluation systems, to combine these techniques with environmental engineering technologies, and to develop new amendment materials.

Rainfall Erosivity Impact on Sustainable Management of Agricultural Land in Changing Climate Conditions

Soil is negatively affected by many degradation factors, of which soil erosion is the most serious, affecting soil quality, crop production, and environmental components. Soil quality is an issue dealt with in the New European Green Deal. In order to meet the set goals, it will be necessary to address soil degradation and water erosion in the agricultural landscape, and increase the area of green infrastructure within the landscape (e.g., fragments of woodland, windbreaks, and grassland). In this context, climate change is also expected to affect the frequency and intensity of torrential rainfall, leading to increased runoff, reduced infiltration, and greater soil loss. Therefore, in this study, we have elaborated the issue of agricultural landscape and erosion, looking at erosion control measures necessary in dealing with existing erosion processes in an intensively farmed area with chernozem soils, and compared these with scenarios assumed for 2050. In these future scenarios, the commonly applied agrotechnical measures will not suffice to keep soil loss at a tolerable level. In the future, it will be necessary to discuss a further reduction in the size of land blocks, with the inclusion of green infrastructure in the landscape. In addition to solving problems of erosion, this would increase diversity in the area and enable sustainable agricultural management.

Improved estimation of nitrogen dynamics in paddy surface water in China

Paddy surface water is the direct source of artificial drainage and surface runoff leading to N loss from rice paddy fields. Quantifying the N dynamics in paddy surface water on a large scale is challenging because of model deficiencies and the limitations of field measurements. This study analyzed the N dynamics and the influencing factors in paddy surface water in the three main Chinese rice-growing regions: Northeast Plain, Yangtze River Basin, and Southeast Coast. An improved first-order kinetic model was proposed to evaluate the total nitrogen (TN) dynamics at a countrywide scale by improving the calculation method of the initial TN concentration (C0) and providing the optimum value of attenuation coefficient (k). The results show that: (1) the average reduction rate of TN concentration on the 7th day after fertilization increased with the growth period (85%, 90%, and 95% during the basal, tillering, and panicle fertilization periods, respectively); (2) the attenuation coefficient k for the growth periods was ranked as follows: panicle fertilization period > tillering fertilization period > basal fertilization period. The Yangtze River Basin had the highest average k value (0.31–0.34), followed by the Southeast Coast (0.24–0.41) and Northeast Plain (0.22–0.30); and (3) the improved first-order kinetic model performed well in the N dynamics estimation (R2 > 0.6). High TN concentration with high fertilizer application amounts and precipitation caused the Yangtze River Basin to have a high N runoff loss risk. The proposed universal model realizes the simulation of N dynamics from a single site to multi-sites while greatly saving multi-site monitoring costs. This study provides a basis for effectively optimizing N management and preventing N loss in rice paddies.

Effects of Distributions of Grass Strips on Soil Erosion in Spoil Tips

The spatial distribution pattern of vegetation is of great significance to the prevention and control of soil erosion in spoil tips. The objective of this study was to evaluate the effects of spatial distributions of grass strips on soil erosion in spoil tips. A field runoff plot (20 m long, 1 m wide, and 0.5 m deep) was used for inflow simulation experiments under four inflow rate patterns (even, rising, falling, and rising–falling) and five grass strip patterns (patterns I–V). Results showed that the runoff reduction benefit (RRB) and soil loss reduction benefit (SLRB) of grass strip patterns were 12.23–49.62% and 12.92–80.54%, respectively. The optimal grass strip pattern was when the grass strips were distributed on a slope in bands (pattern V). In this pattern, the soil and water conservation effects were best, with RRB and SLRB of 43.87% and 58.09%, respectively. The grass strip patterns exhibited a significant time-limited effect on controlling soil erosion. The maximum amount of soil loss reduction for patterns II, III, IV, and V was 93.02, 84.30, 65.86, and 98.26 kg, respectively. Soil loss reduction caused by decreasing runoff (SRR) for grass strip patterns was the main factor controlling erosion. The efficiency coefficient of soil loss reduction caused by decreasing runoff for pattern V was higher than that for the other patterns. The grass strip pattern V (i.e., grass strips were distributed on a slope in bands) should be considered a priority in the prevention of soil erosion in spoil tips. This study can guide the configuration of vegetation control measures for soil and water loss in spoil tips.

Modeling tillage and manure application on soil phosphorous loss under climate change

Phosphorus (P) losses from non-point sources into receiving water bodies play a significant role in eutrophication. Given their failure to adequately control eutrophication in the Lake Erie, conservation recommendations for agricultural watersheds should be reconsidered, particularly under climate change. Using the Environmental Policy Integrated Climate model, the potential impacts on crop yield, surface runoff, tile drainage, and relevant dissolved reactive phosphorus (DRP) losses from manure-amended corn-soybean rotation plots in the Lake Erie basin were estimated for six tillage methods with different mixing efficiencies and manure broadcast application. These were investigated under twelve different regional and global future climate simulations. Tillage alone proved to have only a minor impact on mean corn yield (± 2%). Climate change led to large uncertainties under the single tillage treatment. As a result of the combined effects of biogeochemical processes (e.g., supply) and hydrological (e.g., transport), strong negative relationships (R2 = 0.98) were found between tillage mixing efficiency and DRP loss in surface runoff, tile drainage, and total DRP loss. The impacts of combined manure application (broadcast) and tillage on crop yield and flow volume were similar as those of tillage alone. With respect to total DRP losses, the effects of labile P content change outweighed those of surface runoff or tile drainage change (hydrologic). This resulted in a change in total DRP losses ranging from − 60% to + 151%, with being closely correlated with decreasing tillage mixing efficiency (R2 = 0.94) from moldboard to no-till. Therefore, rotational tillage should be considered for DRP loss reduction and energy saving.

Improving irrigation management on hillslope pastures

Improving irrigation management in hillslope catchments to mitigate water and nutrient losses requires a better understanding of soil hydrology. A field trial was set up in a small catchment on a centre-pivot irrigated dairy farm. Runoff was monitored over two irrigation seasons across a hillslope and at the catchment outlet. Seasonal rainfall variability influenced the start, frequency and amount of irrigation applied. Irrigation stared earlier in the second season due to a large soil moisture deficit. Nearly 40% of the runoff events in the second season were directly linked to irrigation.
 The APSIM model was used to investigate the effects irrigation management on runoff and pasture production. Simulations suggest that changing irrigation could increase pasture yield by 10%, but lead to potentially greater runoff. Using soil moisture to control irrigation improved performance, although where soil moisture was monitored was important. Using frequent and smaller application depths resulted in yield increase and less runoff. Simulation of variable rate irrigation did not produce further gains. The best approach to reduce overall runoff losses was to maintain a soil moisture deficit after irrigation. The impact of changing irrigation management over the whole farm system and its effect on the environment needs further research.

Effect of Thaw Depth on Nitrogen and Phosphorus Loss in Runoff of Loess Slope

Seasonal freeze-thaw erosion is a form of soil erosion caused by the topographical characteristics and climatic factors of the hilly and gully loess regions. Seasonal freeze-thaw can damage the soil pores and cause its bulk density to change. The effects of thawing depth on runoff and Nitrogen and Phosphorus loss on the rainfall erosion of an artificial slope filled with loess soil were analyzed after a rainfall test that simulated the spring thaw period in China. The results showed that: (1) The maximum runoff yield was 33.35 mm at 4 cm thawing depth, and the minimum was 12.95 mm at 6 cm thawing depth. With the increase in runoff time, the slope infiltration rate had a decreasing trend. The loss rate of available and total Phosphorus increased with the increase in runoff rate. The rate of increase was fastest when the thawing depth was 4 cm. (2) The relationships between runoff rate and Nitrogen loss and Phosphorus loss rate can be explained by linear regression equations, and the loss rate increased as the runoff rate rose for all thawing depths. Within the 0–6 cm thawing depths, the loss of total phosphorus was the largest when the thawing depth was 4 cm, and the loss of available phosphorus was the smallest when the thawing depth was 6 cm. At the shallower thawing depths, the available Nitrogen loss represented a smaller proportion of the total Nitrogen loss compared to nitrate Nitrogen loss. However, there was a gradual rise in the available Nitrogen proportion in the total amount of inorganic Nitrogen as the thawing depth increased. (3) Total Phosphorus was the available Phosphorus with a quadratic function relationship with runoff energy and runoff power. Runoff energy mainly affected the total Nitrogen and available Nitrogen loss in runoff, whereas runoff power mainly affected total Nitrogen loss in runoff. The results of this paper can improve the understanding of runoff and Nitrogen and Phosphorus loss caused by runoff during freeze-thaw conditions.

Field scale discharge and water quality response, to drainage water management

Subsurface (tile) drainage, while necessary for viable agricultural crop production in the humid, poorly drained regions of the world, has been linked to offsite nutrient transport, culminating in harmful algal blooms and hypoxia in downstream waterbodies. Drainage water management (DWM), also known as controlled drainage, has been promoted as a method to reduce nitrogen (N) and phosphorus (P) loss from field scale tile drainage; however, subsequent changes in surface runoff and associated water quality have not been explored. Four years of surface and subsurface discharge, N, and P loss from two sets of paired field sites in northwest Ohio, USA were evaluated using a before-after control-impact (BACI) design to quantify the impact of DWM. Mean event surface runoff was greater (significant at one site) under DWM while tile drainage discharge was less at both sites but not significant. There was no significant difference in surface nitrate-N (NO3--N) loss; however, significant reductions in tile NO3--N loss under DWM were measured at both sites. Similar to discharge, dissolved reactive P (DRP) loss measured in surface runoff was greater under DWM (significant at one site), while no significant differences were noted in mean event tile drainage DRP loss. Total P (TP) surface runoff losses were significantly greater under DWM at the site with significantly greater surface runoff, while DWM reduced tile drainage TP loss at only one site. These findings suggest that DWM reduced tile NO3--N loss, while also highlighting that any benefit from DWM with respect to tile DRP or TP loss could be negated in part by increased surface losses. Furthermore, these findings emphasize the need to understand the natural resource concern to which the practice is targeted and also call for additional research on DWM implementation that includes surface runoff across a range of soil textures, cropping management, and climates.

Apparent variations in nitrogen runoff and its uptake in paddy rice under straw incorporation

Straw incorporation is a widespread practice to promote agricultural sustainability. However, the potential effects of straw incorporation with the prolonged time on nitrogen (N) runoff loss from paddy fields are not well studied. The current study addresses the knowledge gap by assessing the effects of straw incorporation on the processes influencing N runoff patterns and its impacts on crop yield, N uptake, total N (TN), and soil organic matter (SOM). We conducted field experiments with rice (Oryzasativa L.)–wheat (Triticumaestivum L.) rotation, rice–tobacco (Nicotianatabacum L.) rotation, and double-rice cropping in subtropical China from 2008 to 2012. Each rotation had three N treatments: zero N fertilization (CK), chemical N fertilization (CF), and chemical N fertilization combined with straw incorporation (CFS). The treatment effects were assessed on TN runoff loss, crop yield, N uptake, soil TN stock, and SOM. Results showed that TN runoff was reduced by substituting part of the chemical N fertilizer with straw N in the double rice rotation, while crop N uptake was significantly (P<0.05) decreased due to the lower bioavailability of straw N. In contrast, in both rice–wheat and rice–tobacco rotations, TN runoff in CFS was increased by 0.9–20.2% in the short term when straw N was applied in addition to chemical N, compared to CF. However, TN runoff was reduced by 2.3–19.3% after three years of straw incorporation, suggesting the long-term benefits of straw incorporation on TN loss reduction. Meanwhile, crop N uptake was increased by 0.8–37.3% in the CFS of both rotations. This study demonstrates the challenges in reducing N runoff loss while improving soil fertility by straw incorporation over the short term but highlights the potential of long-term straw incorporation to reduce N loss and improve soil productivity.

Direct Comparison of Runoff of Residual and Knockdown Herbicides in Sugarcane Using a Rainfall Simulator Finds Large Difference in Runoff Losses and Toxicity Relative to Diuron

Direct Comparison of Runoff of Residual and Knockdown Herbicides in Sugarcane Using a Rainfall Simulator Finds Large Difference in Runoff Losses and Toxicity Relative to Diuron

Research progress on soil soluble organic nitrogen

Soluble organic nitrogen (SON) and inorganic N are two crucial nitrogen (N) forms in the cycling of N within terrestrial ecosystems, acting as either a "source" or a "sink" to the environmental N release. The mineralization, retention, leaching, and plant absorption of N in terrestrial ecosystems are closely related to SON. As a result, the role of SON in soil material circulation and nutrient flow has attracted much attention and has become one of the hotspots in various research fields, such as ecology, environmental science, soil science, and hydrology. We reviewed the research progress on soil SON, including the definition and quantification, the size and composition, the absorption and utilization by plants and microorganisms, the sources and influencing factors, and the transformation, migration, and leaching loss of SON. SON is a complex collection of multi-component soluble organic matter, mainly as recalcitrant components (difficult to degrade), with relatively low proportion as labile components (easily degradable). Due to the difference in the turnover time among recalcitrant and labile components, the roles of SON in N cycling and turnover cannot be fully represented by the SON quantity. Therefore, to accurately reflect the role of SON in N turnover, N uptake, and N leaching, it is necessary to establish new methods and distinguish between recalcitrant and labile SON components in future studies. When studying the role of SON in N conversion and N absorption, it is essential to focus on its labile components. When studying the contribution of soil SON to N leaching or runoff loss, it is necessary to focus on the recalcitrant components.

Improvements to the soil nitrate quick test for California small grains

Small-grain crop growers need to match their crops' nitrogen (N) needs with fertilizer applications. This can be challenging because small grains are grown under diverse conditions and their growing season interacts with unpredictable precipitation. Resulting conditions can lead to nitrate-N leaching and runoff losses. More widespread and accurate soil N testing could help growers improve N fertilizer use efficiency, reduce the risk of N loss, and fulfill regulatory requirements. Soil samples from across California small-grain growing regions were tested with a soil nitrate quick test as well as standard laboratory procedures. The quick test is inexpensive and easy to use, and it provides rapid results. A correction factor was developed to convert the quick test values to lab and fertilizer equivalents. The correction factor is based on site-specific soil bulk density and the extracting solution used. An interactive webtool was developed that integrates this information for users. The quick tests provide accurate, real-time estimates of soil nitrate-N in the field to help improve fertilizer use efficiency and reduce N losses.

Impact of Cover Crops on Water Runoff and Soil Loss in Compacted Oxisol

Impact of Cover Crops on Water Runoff and Soil Loss in Compacted Oxisol

Effect of Mulching and Tied Ridge on Crop Production and Soil Improvement in Dry Land Areas

Rain fed crop production in dryland areas is unreliable due to high evapo-transpiration, high run-off rates, delay onset, and early cessation of rains. So soil moisture deficiency is one of the primary factors that limit crop production in the area. Soil conservation is another important issue in dryland areas because high run-off rates leads to severe soil erosion. Due to shortage of soil moisture there have been attempts to optimize crop yield by planting drought-tolerant crops, particularly maize, sorghum and millet. This is not enough because crop failure due to water stress is still observed in dry lands. Therefore the proper use of soil moisture conservation structures like tied ridge helps to reduce the runoff rate, nutrient losses from soil and improve the soil moisture for plant growth which in turn, boost the productivity of land and plants. In addition to tied ridge mulching is a good practice used to reduce soil erosion and enhance water conservation. Tied ridge is one of the structures used to reduce water runoff and increase infiltration of rain water to the soil. It is a form of micro-basin tillage which consists of ridging the soil typically to heights of 0.20 to 0.30 m and is blocked with earth ties spaced considering slope of the land. Tied-ridging increased soil water by more than 25% compared to the traditional tillage practice in northern Ethiopia. It has been reported that tied ridging is beneficial for increasing crop yield. Tied-ridging increased sorghum grain yield by more than 40% compared to the traditional tillage practice in northern Ethiopia. It has beneficial effects of reducing runoff loss and soil loss. Mulching is also on the positive side of the balance in dry land. When adequate residues are available and conservation tillage is used, soil erosion is greatly reduced and water conservation is enhanced. Management of crop residues on the farm lands increased the grain yields of maize, sorghum and wheat crops both by improving soil fertility and conserving water at Haramaya area. Mulch conserved more water and led to higher dry matter and grain yields of maize compared to minimum tillage.

Within-Field Variability in Nutrients for Site-Specific Agricultural Management in Irrigated Cornfield

HighlightsPhosphorus and nitrogen in soil and plants varied during the growing season across the cornfield.Spatial variability in nutrients caused spatial variability in plant growth and crop yield across the cornfield.Hydrological characteristics and soil hydraulic properties were responsible for spatial variability in nutrients.Need to consider spatial variability in nutrients in delineating management zones before adopting management practices.Abstract. The adoption of precision agricultural practices in Alabama has been increasing in recent years. Although challenging, understanding nutrient variability in agricultural fields is important for site-specific management. This study investigated phosphorus (P) and nitrogen (N) variability in an irrigated cornfield located in the Town Creek Watershed of Tennessee Valley Region of Alabama, USA during the 2019 growing season. Three different irrigation management zones (high yield-HY, moderate yield-MY, and low yield-LY) were delineated based on ten years of historical records of crop yield, soil texture, and measured topography using the Management Zone Analyst (MZA) software. The soil samples at 0 to 15 cm, 15 to 30 cm, and 30 to 60 cm depths were collected five different times during the 2019 growing season. Both manure and inorganic fertilizer were uniformly applied during the growing season. At all soil depths, HY and MY zones had higher soil nutrient concentrations than the field average nutrient concentration. However, the LY zone had below field average soil nutrient concentration in the entire soil profile. The plants (above-ground) in HY and MY zones had higher than average nutrient concentrations and the plants in the LY zone had lower than average nutrient concentrations throughout the cornfield. This site-specific nutrient variation in these zones was due to within-field terrain attributes, differences in soil properties, and surface runoff losses. A significant difference was recorded in the corn yield in the HY and LY zones of the field. Two extreme groups of nutrients were found in the cornfield similar to irrigation management zones (HY and LY). A zone with a higher yield also had higher soil and plant nutrients in the zone (HY), and a zone with a lower yield also had lower soil and plant nutrients in the zone (LY). Incorporating nutrient variability for site-specific management in management zone delineation can help with reducing nutrient application, nutrient loss, and improving yield. This study supports the adopting of precision agricultural management practices based on in-field nutrient variability. Keywords: Corn, Crop yield variability, Irrigation, Management zones, Nitrogen, Nutrient variability, Phosphorus, Site-specific management, Topographical wetness index (TWI).

Phosphorus Flows, Surpluses, and N/P Agronomic Balancing When Using Manure from Pig and Poultry Farms

The pig and poultry industries continue to grow across the world and together they provide the majority of meat consumed. The European Union (EU) in particular has the highest global relative meat production by monogastrics (i.e., pig and poultry). The fate of phosphorus (P) in pig and poultry farming was studied, accounting for P content in feed, animals, manure, soil, and runoff. P input from manure, and P offtake in crops receiving manure, were plotted against each other to arrive at “safe” P loading rates, in order to minimize soil P surpluses along the lines of the EU Nitrogen Expert Panel in their work with nitrogen (N). However, it was observed that it is the N/P ratio and the background soil P levels that determine whether a certain manure will end up producing surplus levels of soil P. Critical N/P weight ratios were derived over different crop P offtake rates when applying stored manure to croplands. At spreading rates of 170 and 250 kgN/ha/year and a crop P offtake of 15 or 30 kgP/ha/year, stored pig and chicken manure result in soil P surpluses. An important factor in determining effective N/P ratios is the plant availability of N in stored manure, which runs at around 47%, estimated from previously published results. The minimization of N losses to the atmosphere and to groundwater in housing, storage, and spreading of manure has a major impact on the N/P weight ratio of the manure that ends up on fields. In most cases, half of the ex-animal N content has been lost in stored or degraded manure, with N/P weight ratios running at two and less. Following only the EU Nitrates Directive, which allows for a maximum of 170 kgN/ha/year in NVZs (Nitrate Vulnerable Zones), will often result in soil P surpluses leading to runoff losses to adjacent water bodies. Therefore, for the pig and poultry industries to continue thriving, measures are required to better manage manure, including improved storage and spreading techniques, acidification, separation, struvite extraction and ammonia stripping of pig slurry, and drying and pelleting of poultry litter. This way, excess manure and derived biofertilizers from animal farms can find their way back into the commercial market, instead of ending up as legacy P in watersheds and coastal zones.