| | Introduction | Study methods | Findings | Conclusions | Project support | Publications | For more information
Introduction
The livestock sector is a significant part of Alberta's agricultural industry. The livestock industry in general, and the beef feedlot sector in particular, has grown significantly during the past several years. Global market opportunities may support continued expansion of Alberta's livestock sector. A large livestock industry generates a considerable amount of manure, which must be managed in a responsible manner. The application of manure on agricultural land is the most effective method of using manure. Generally, manure is applied on cultivated land. However, in areas where suitable cultivated land is not available or because of convenience, the use of forage land is an alternative for manure application. However, research in Alberta on the effects of manure on soil quality, water quality, and crop production has mainly focused on cultivated land. There has been limited research on the effects of manure application on forage crops in Alberta in terms of soil properties, forage yield, and forage quality. The objective of our 5-yr (1996 to 2001) study was to determine the effects of repeated, annual applications of beef and hog manure on soil quality, forage yield, and forage quality.
Study Methods
The 5-yr field study was carried out in southern Alberta. One site was started in 1996 near Lethbridge under irrigated alfalfa (Medicago sativa L.), and a second site was started in 1997 near Airdrie under rainfed timothy (Phleum pratense L.). The experimental design at both sites included two manure application times (spring and fall), two manure types and application methods [surface-applied, solid, cattle (Bos taurus) manure and injected, liquid, hog (Sus scrofa) manure], and five application rates. Annual (spring and fall) manure rates were 0, 31, 61, 92, and 122 Mg ha-1 (wet-weight basis) for the solid manure, and 0, 42, 84, 126, and 168 Mg ha-1 (wet-weight basis) for the liquid manure. Because of the differences in the amounts applied between the two manure types, the manure application rates are referred to as rate 0, rate 1, rate 2, rate 3, and rate 4. Soil samples were collected to 1.5 m depth at the start of the study at both sites and in the spring of each year during the study. Soil samples were analysed for extractable nitrate-N, ammonium-N, phosphate-P, sodium, potassium, and sulphate-S, pH, electrical conductivity, and organic matter. Forage-yield data were collected from 1996 to 2000 at the Lethbridge site and from 1997 to 2000 at the Airdrie site. Tissue samples from both sites from 1997 to 2000 were analysed for protein, acid detergent fiber, nitrate, phosphorus, calcium, magnesium, sodium, potassium, copper, selenium, sulphur, zinc, manganese, aluminum, boron, and iron. Because of the way the study was started at the two sites, the application time factor (spring versus fall) could not be statistically compared. The data were analysed by site and by application time. The main factors were manure type and manure rate, and year was treated as a split treatment in the statistical analysis of the data.
Findings
The application of beef or hog manure on irrigated alfalfa and rainfed timothy significantly affected soil chemistry. Soil extractable nitrate-N increased in the soil with evidence of nitrate leaching down the soil profile at both sites. The differences between beef and hog manure at the two sites could be explained, in part, by differences in total nitrogen applied between the manure types and by the potentially greater loss of volatile nitrogen from the surface-applied, non-incorporated, beef manure. Extractable phosphate-P in the soil generally increased, but higher levels of phosphate-P remained in the top 15 cm of soil. Extractable potassium was also increased, but only for beef-manure application. About four to eight times more potassium was added from beef-manure applications compared to hog-manure applications. Extractable sodium content was increased at both sites. Beef manure had a larger affect than hog manure at the Lethbridge site, and this was probably because a little more than eight times more sodium was added from beef manure at this site. Manure application did not affect sulphate-S content at the Lethbridge site, whereas sulphate-S content was significantly increased in the 0- to 30-cm depth at the Airdrie site. Spring-applied manure essentially did not affect soil electrical conductivity at the Lethbridge site. However, the fall-applied manure significantly increased soil electrical conductivity. Similar results were observed at the Airdrie site. Soil organic matter was not affected by manure application at the Airdrie site, whereas soil organic matter was increased in the 0- to15-cm depth at the Lethbridge site. Beef manure had a greater effect than hog manure, and this is probably because three times more organic matter was added to the beef-manure plots.
The application of manure had no significant effect on alfalfa yield at the Lethbridge site in 1996 to 1998, regardless of the manure type and the time of application. In 1999, most manure treatments yielded significantly higher than the control, and in 2000 all manure treatments yielded higher than the control. After four or five annual applications of manure, there was no nutrient advantage of applying more than the lowest rate used on alfalfa. There were significant treatment-by-year interactions for the fall- and spring-applied treatments. There were no significant differences among the four rates for each manure type and no differences between the two manure types, regardless of the application time and year. Timothy yield was not significantly different from the control for the spring-applied treatments in 1997 at the Airdrie site. In 1998 to 2000, manure treatments often had significantly higher yield than the control. The spring-applied treatments showed no differences between the two manure types. Generally, yield increased as the spring-applied manure rate increased from rates 1 to 3. Rate 4 was not significantly different than rates 2 and 3, and there was a tendency for yield from the rate 4 treatment to be less than rate 3. This may be an indication that a yield depression occurred with the high application rate.
The effects of manure application on tissue quality varied according to measured parameter, site location, year, manure type, and manure rate. There were manure-by-rate, manure-by-year, and rate-by-year interactions. Sixteen crop-tissue parameters were measured, and of these, protein, acid detergent fiber, nitrate, phosphorus, calcium, magnesium, sodium, potassium, copper, selenium, sulphur, zinc, and manganese were significantly affected by manure application. Only boron, iron, and aluminum were not significantly affected by beef or hog manure application. The concentration of most parameters that were significantly affected increased when manure was applied. The exception was selenium, which was the only parameter that decreased in concentration with the application of manure. The cumulative effect of annual manure applications was apparent, because the effect became more pronounced for many of the increases in successive years. Concentration of the parameters that increased with added manure tended to be more pronounced for timothy than for alfalfa under the conditions of the study.
Conclusions
The overall conclusion of our study is that surface-applied solid beef manure and injected liquid hog manure can be effectively applied to forage land. This is particularly good for liquid manures, because injection methods are considered good practices to reduce odours, reduce nitrogen losses, and help prevent nutrient losses by surface runoff. Our results also showed that manure application significantly affected soil quality, forage yield, and forage quality. In terms of soil quality, several nutrients of environmental concern accumulated in the soil, such as nitrate-N and phosphate-P, and an increase in soil salinity was observed. Based on electrical conductivity alone, as a measure of salinity, the annual application of manure at the higher rates is not sustainable with time under the conditions of the study. Annual applications should not exceed the lowest rates used in the study. The cumulative effect of 4 to 5 yr of manure application generally did not show differences among manure application rates (other than the control) in terms of yield increase. Long-term manure application above the lowest rates used in this study will not add any significant benefit to increase yield. There was some indication that the highest manure rates may have suppressed yield relative to the second highest manure rates for timothy at the Airdrie site. For the most part, the application of manure on forages did not have any negative effect on alfalfa and timothy forage quality. The comparison between beef and hog manure was variable and one type was not found to be better than the other. The physical action of injecting hog manure into forage land did not have a deleterious effect on crop yield. Many differences among beef and hog manure treatments, in terms of soil chemistry and tissue quality, could be explained by the differences in the nutrient load in the two types of manure. Statistically, the spring- and fall-application treatments could not be compared; however, a qualitative comparison indicated there were minimal differences between spring and fall applications.
Project Support
Funding for this study was received from:
- Canada-Alberta Beef Industry Development Fund
- Canada-Alberta Hog Industry Development Fund
- County of Lethbridge No. 26
- Foothills Forage Co-op Association
- Municipal District of Rocky View No. 44.
Publications
Published Paper
Olson, B.M. and Papworth, L.W. 2006. Soil chemical changes following manure application on irrigated alfalfa and rainfed timothy in southern Alberta. Canadian Journal of Soil Science 86: 119–132.
Final Technical Report
Manure Application on Forages
For More Information
Barry Olson
Alberta Agriculture and Forestry
Lethbridge, Alberta
Toll free 310-0000
Phone: 403-381-5884
Email: barry.olson@gov.ab.ca |
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