Nutrient Management Water Quality Use

J. L. Hatfield

United States Department of Agriculture, Agricultural Research Service, Ames, Iowa, U.S.A.

INTRODUCTION

Animals generate a valuable source of nutrients in both organic and inorganic forms. Nutrients in manure can be a valuable soil amendment; however, if manure is misused, it can be a potential water quality problem. Water quality is a primary concern among environmental issues; manure application is the focus of this article.

MANURE NUTRIENTS

Nutrients vary among species, manure handling, and storage systems as shown in Table 1. Nutrient content is affected by species, diet, age, sex, manure storage system, and length of time in storage. Values shown in Table 1 illustrate the nutrient content in different manure storage systems but do not represent the full range of variation within a species or among manure storage systems.

These data provide an indication of the variation among species and the need for nutrient management systems to consider animal production systems and manure storage systems before making assumptions about the best management system. The goal in nutrient management is to develop a system in which manure nutrients may be applied to the soil to supply the crop needs without being a potential environmental problem.

WATER QUALITY CONCERNS

In nutrient management, water quality concerns focus on phosphorus (P) and nitrate-nitrogen (NO3-N). Broadcast manure on the soil surface provides for potential surface runoff conditions, particularly when rain occurs shortly after application. In a 2001 study, broadcasting manure resulted in the greatest potential for surface runoff of soluble P.[2] Kleinman and Sharpley[3] compared dissolved reactive phosphorus from three manures at six rates under simulated rainfall and found that dissolved reactive phosphorus loss was related to runoff and manure application rate. Soluble P losses were a function of the type of manure, the application rate, and soil type. Broadcast manure on the soil surface increases the potential for surface runoff into nearby surface water bodies. In addition, surface runoff of manure may provide pathogens that are present in manure a pathway into nearby water bodies. There are few studies of this problem and the evidence is insufficient to provide a set of factors that contribute to pathogen movement.

Incorporation of manure into the soil greatly reduces the chances of surface runoff. Tabbara[4] showed that incorporation of manure or fertilizer 24 hours before a heavy rainfall reduced both dissolved reactive P or total P concentrations by as much as 30% to 60% depending on the nutrient source and application rate. The incorporation process moves P below the volume of soil eroded under high rainfall events. To reduce potential surface losses of P, manure should be incorporated on soils with intensive erosive rain, recent extensive tillage, or little or no surface residue. Incorporation of manure will reduce the likelihood of surface runoff of P and protect surface water from excess P levels; however, the process of incorporating manure may increase the potential for sediment loss from the soil. The development of management practices that protect soil from surface runoff will decrease potential losses of manure P into nearby water bodies.

Incorporation of manure may lead to NO3-N leaching because nutrients placed below the surface mixing layer are in a soil volume where leaching of nutrients can occur. NO3-N present in the manure may be moved into deeper soil layers by soil water. However, there is no evidence that this is a direct result of manure application. Incorporation of manure changes the availability of nutrients in the soil profile. Nutrients present in manure are in the organic form and the conversion into available forms is a function of biological activity and time in the soil profile. Klausner et al.[5] developed a method to estimate the decay rate for organic nutrients from dairy manure that has worked well for this species over a range of environmental conditions. One of the challenges for manure management is to determine the temporal patterns of nutrient availability from different manure types and species. Jokela[6] showed that NO3-N levels were actually lower in soils treated with dairy manure compared to commercial fertilizer because of the slower release of NO3-N from manure.

Nutrient patterns in manured soils can lead to potential water quality problems; however, these can be managed through a proper rate of application and incorporation.

Table 1 Nutrient content in solid and liquid manure for different species and manure handling systems

Solid manure storage Liquid manure storage

Species

Dry matter %

Total N

P2O5

K2O

Dry matter %

Total N

P2O5

K2O

(g/kg)

(g/l)

Beef

50

10.5

9.0

13.0

9

3.5

2.2

3.1

Dairy

21

4.5

1.5

3.0

8

3.7

1.8

2.3

Poultry

18

19.0

22.5

12.5

10

7.2

5.4

3.6

Swine

76

6.5

4.0

2.5

4

4.3

3.0

Water quality problems can be reduced through relatively simple management practices that increase nutrient availability to the crop and decrease the potential for offsite movement through runoff or leaching.

EFFECT OF MANURE ON SOIL PROPERTIES RELATED TO WATER QUALITY

Addition of manure to soil causes changes in the soil properties1-7,8-1 that reduces the likelihood of water quality problems. Water infiltration rate, soil water-holding capacity, cation exchange capacity, bulk density, organic matter, biological activity, and plant availability of nutrients are changed by manure additions. These changes required at least five years of manure additions to the soil. A positive impact on water quality is derived from increased water infiltration rates and water storage capacity. Surface runoff occurs in soils that quickly develop a surface seal and ponding begins on the soil surface leading to the development of small rills that transport water along the surface. Manure-amended soils have a larger infiltration rate and more rainfall can enter the soil before saturation occurs. This change is not a direct effect of manure addition but a combination of increased biological activity and organic materials that create a more stable soil particle that has a higher soil water content before becoming saturated. The higher waterholding capacity of soil allows more absorption before the profile is saturated. Eghball et al.[9] concluded that the increased intensity of rainfall could cause surface runoff but changes in the soil properties from manure could offset water quality problems.

Addition of manure to soil not only changes the soil properties but also restores the soil to a higher level of soil productivity. Freeze et al.[10] found that the application of manure to eroded soil was of greater benefit than application to noneroded soils. Changes in soil

Fig. 1 Conceptual diagram of nutrient flows in the MINAS systems for the Netherlands. (Adapted from Ref. 11.)

properties are more detectable in eroded soils. These effects of manure can be realized with all sources and types of manure. Often the water quality problems that occur in agriculture are from soils that are in a degraded state and restoration of soil properties will benefit the environment.

NUTRIENT ACCOUNTING FROM MANURE SOURCES

To achieve water quality goals and manure application requires the proper amount of nutrients added to the soil to supply crop requirements. The components in a nutrient budget are rates of crop removal, change in the soil nutrient content, and amount supplied from manure. In the Netherlands, nutrient accounting systems have been developed for livestock and cropping systems. Ondersteijn et al.[11] described the mineral accounting system (MINAS) and provided a framework for nutrient accounting (Fig. 1). Manure that is produced is accounted for through the MINAS approach to ensure that both an economic and environmental quality goal is achieved. Development of nutrient management guidelines for producers to help guide their decisions can have a positive impact on environmental quality.

CONCLUSION

Nutrient management programs must have a positive impact on water quality. The challenge for producers is to understand the nutrient balance in the soil and to reduce the risk of surface runoff of manure. The challenge for science is to increase our understanding of the value of manure in the soil and in the restoration of eroded soils to a higher level of productivity. Improved methods for sampling manure to determine the nutrient content from individual farms and for manure application that incorporates manure to reduce erosion and enhance the value of manure on soil properties will benefit livestock, crop producers, and the environment.

REFERENCES

1. MWPS (MidWest Plan Service). Manure Storages. Ma nure Management System Series. MWPS 18, Section 2. MidWest Plan Service. Iowa State University: Ames, IA, 50011 3080, 2001.

2. Zhao, S.L.; Gupta, S.C.; Huggins, D.R.; Moncrief, J.F. Tillage and nutrient source effects on surface and subsurface water quality at corn planting. J. Environ. Qual. 2001, 30, 998 1008.

3. Kleinman, P.J.A.; Sharpley, A.N. Effect of broadcast manure on runoff phosphorus concentrations over succes sive rainfall events. J. Environ. Qual. 2003, 32, 1072 1081.

4. Tabbara, H. Phosphorus loss to runoff water twenty four hours after application of liquid swine manure or fertilizer. J. Environ. Qual. 2003, 32, 1044 1052.

5. Klausner, S.D.; Kanneganti, V.R.; Bouldin, D.R. An approach for estimating a decay series for organic nitrogen in animal manure. Agron. J. 1994, 86, 897 903.

6. Jokela, W.E. Nitrogen fertilizer and dairy manure effects on corn yield and soil nitrate. Soil Sci. Soc. Am. J. 1992, 56, 148 154.

7. Sommerfeldt, T.G.; Chang, C. Changes in soil properties under annual applications of feedlot manure and different tillage practices. Soil Sci. Soc. Am. J. 1985, 49, 983 987.

8. Sommerfeldt, T.G.; Chang, C. Soil water properties as affected by twelve annual applications of cattle feedlot manure. Soil Sci. Soc. Am. J. 1987, 51, 7 9.

9. Eghball, B.; Gilley, J.E.; Baltensperger, D.D.; Blumenthal, J.M. Long term manure and fertilizer application effects on phosphorus and nitrogen in runoff. Trans. ASAE 2002, 45, 687 694.

10. Freeze, B.S.; Webber, C.; Lindwall, C.W.; Dormaar, J.F. Risk simulation of the economics of manure application to restore eroded wheat cropland. Can. J. Soil Sci. 1993, 87, 267 274.

11. Ondersteijn, C.J.M.; Beldman, A.C.G.; Daatselaar, C.H.G.; Giesen, G.W.J.; Huirne, R.B.M. The Dutch mineral accounting systems and the European nitrate directive: Implications for N and P management and farm perfor mance. Agric. Ecosyst. Environ. 2002, 92, 283 296.

Weight Loss All Star

Weight Loss All Star

Are you looking to lose weight or even just tone up? What is stopping you from having the body you want and help you feel great at the same time? I created Weight Loss All-Star for all those wanting to lose weight, and keep the weight off. I know how hard it is to do diets and stick with them, and get the motivation to get up and exercise.

Get My Free Ebook


Post a comment