| | This is an excerpt from the final report for AARI Project #329910
Executive Summary
As the Alberta livestock industry continues to expand, manure management becomes an imperative issue.
Many research results have demonstrated that manure contains plant essential nutrients; therefore, it can be a resource for crop production. On the other hand, overuse of manure on agricultural land can cause nutrient enrichment in soils, consequently leading to surface/groundwater eutrophication.
The objectives of this research project was to determine the best use of manure as a resource to enhance crop production and the soil resources; and, at same time minimize the environmental risks caused by use of manure on arable land with Alberta climate, soil and crop management conditions.
From 1998 to 2000, the Agronomy Unit had undertaken the research project "Manure: Enhancing Crop Production and the Soil Resource" funded by Alberta Agricultural Research Institute (AARI). The project consisted of three components - a field research experiment, a groundwater monitoring and testing experiment, and a greenhouse experiment. In addition, an economic analysis of manure value was conducted.
In the field research experiment, there were six field experimental sites; four were established before 1998 prior to this project.
- In 1994, two cattle manure sites were set up at Lacombe and Ponoka with the application rates ranging from 0 to 120 T manure/ha. At these two sites, there were nitrogen fertilizer treatments with application rates from 0 to 180 kg N/ha.
- In 1995, two sites were established at Calmar and Devon with treatments of low annual cattle (20 T/ha) and hog (15 m3/ha) manure application, and 1-in-3 year high cattle (60 T/ha) and hog (45 m3/ha) manure application.
- Two sites were established in 1998 located at Ellerslie and Cooking Lake with annual hog manure application rates of 0, 15, and 30 m3/ha, in comparison with the 1-in-3 year application rate of 45 and 90 m3/ha. At these sites, there were nitrogen fertilizer treatments with rates from 0 to 120 kg N/ha.
In addition, "best management practice" (BMP) treatments (combination of N fertilizer and manure) were included at the Lacombe, Ponoka, Ellerslie, and Cooking Lake sites.
Soil samples were taken, prior to the start of the experiment in the spring of 1998 and again in the fall of 2000 after field work was completed. Crops grown at the Ellerslie and Cooking Lake sites were wheat, canola, and peas; the Calmar and Devon sites included triticale, barley, and wheat; and silage barley, barley/triticale blend, and wheat were grown at the Lacombe and Ponoka sites. Crops were harvested each year, dried, weighed and then analyzed for grain and silage N and P content.
A groundwater monitoring well was established in each treatment in the field experimental sites at Lacombe and Ponoka. Groundwater samples were taken three times (May, July and September) during the growing season every year over three years. Nitrate concentration in the water samples was determined.
For the greenhouse experiments, manured soils were taken from research plots at the Lacombe, Ponoka, Calmar, and Devon sites and two research sites near Lethbridge. Soils were added with manure, hog (45 m3/ha) or cattle (60 T/ha), depending on previous manure treatments. Soils were either incubated or seeded to barley for 75 days. Soil and plant samples were taken at 25-day intervals. All soil samples were analyzed for their nutrient, organic matter content, electrical conductivity (E.C.), and pH.
An economic analysis was conducted to determine the value of manure based on the yield and fertilizer price. Using yield and grain price, an economic transportation distance of manure was also calculated.
Field and greenhouse results showed that manure was a good nutrient source for crop growth; however, availability of nutrients to crop production was different between hog and cattle manure.
Nutrients in hog manure were quickly available to crops. Because of this, high rates of hog manure application could potentially result in NO3-N and PO4-P in groundwater. Results showed that relatively high NO3-N and PO4-P concentrations were found in the 30-60 cm soil depth, indicating downward movement of N and P due to high hog manure application.
Nutrients in cattle manure were slowly available to plants. In general, there was little benefit to crop growth from the current cattle manure application; however, there was a strong residual effect from cattle manure application. The non-composted cattle manure, if applied, immobilized N in soil for the first 50 days after application.
The cattle manure application apparently increased 1.5% soil organic matter content (an average of all manure treatments at the four cattle manure sites and the average rate was 60 T/ha) with a rate of 8.3 T/ha/yr/100 T manure application, over six years. There was an increase in total N and P (111 and 55 kg/ha/yr/100 T manure application, respectively).
Hog manure application also increased soil organic matter. Likewise, there was a 1.1% organic matter increase from hog manure application (an average of all manure treatments at the Calmar and Devon sites, and the average rate was 15 m3/ha) with a rate of 2.5 T/ha/yr/10 m3 hog manure. There was an increase in total N (0.03%) and total P (0.01%) over six years with a rate of 67 kg N/ha/yr/10 m3 and 22 kg P/ha/yr/10 m3 hog manure.
Application of both manure sources led to an increase of extractable P (Miller-Axley) in the soil. In the greenhouse experiments, cattle manure contributed more soil P than did hog manure. After years of cattle manure application, crop growth and removal did not affect concentration of Miller-Axley extractable P, but water extractable P declined. Water extractable P was more sensitive to crop removal than with the Miller-Axley extractable P. Annual manure application resulted in more P in soil, as compared to the 1-in-3 year application. During the three-year experiment at the Lacombe and Ponoka sites, there were only 11 water samples (total water samples was 585 in three years) that exceeded the national water quality standard in nitrate (10 mg NO3-/L).
Manure application increased soil water holding capacity. The water holding capacity from the cattle manure application increased to 35.5% (60 T/ha/yr) from 26.4% of the Check treatment, a 34.5% increase. In comparison, the 15 m3/ha/yr hog manure application only increased water holding capacity to 28.9%, a 10.7% increase over 26.1% of the Check treatment.
The economic analysis of the yield generated from manure application indicated that the marginal return from using manure was 8.8 to 10.8 for hog manure and 5.5 for cattle manure. Based on cost effect, when applied 1-in-3 years, there were more profits when growing canola or wheat in the first year. This was especially true with the hog manure application.
The BMP treatments in the field experiment did not show the merit of combining manure with chemical fertilizers, for yield increase or reduction of nutrient accumulation in soils. The results indicated, however, after several years of manure application, one only needed to apply N fertilizer for crop production.
In conclusion, manure is a valuable resource if managed properly. Proper manure management includes application time, crop rotation, and application rate. Using the 1-in-3-year application strategy, canola and wheat should be grown in the first year in order to maximize profits. The recommended best management practice would be to stop manure application after several years (four to five years), and then match nitrogen fertilizer for crop production after that. This practice can optimally use manure phosphorus and reduce its content in soil. |
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