Project: MLMMI 02-01-07
Objective
To determine the variability in soil nitrate nitrogen and phosphorous levels of manured and non-manured fields in grass forage production.
Performer
G. Plohman/S. Vielfaure
Elite Swine Inc./Hytek
Details
Status: Completed
Started: 2002-06-21
Completed: 2002-07-08
Funding Partners: who have contributed to MLMMI in support of this project:
Manitoba Pork Council - $14,200
Industry groups - $14,200
Amount Funded: $28,400.00
Performer Funded: $57,650.00
Total Cost: $86,050.00
Activity
Final report due July 15, 2002; received July 8/02.
Summary
This survey study was initiated to investigate the nutrient status of agricultural soils in South Eastern Manitoba that have a history of hog manure application and to compare these soils to similar soils that have not received manure. The land areas that were studied were characterized by coarse textured, low agricultural capability soils in grass forage production. The study locations would be considered representative of soil landscapes commonly known as the Poppleton, Pelan and Malonton soil associations.
The variability in soil nitrate nitrogen and phosphorus with depth was determined at twelve manured locations and six non-manured locations each about eighty acres in area.
Three soil-sampling procedures were conducted at each field location. The first consisted of individually sampling fifteen randomly selected sites identified with global positioning coordinates. The second involved taking a sub-sample from each of these fifteen sites for a single composite sample. The third procedure consisted of selecting, at the investigator's discretion, four of the random sites to represent the whole field (benchmark sampling).
The study found that there was a higher concentration of nitrogen and phosphorus to a depth of sixty centimeters in manured fields, especially for phosphorus when compared to non-manured fields. However, at some of the non-manured sites there was evidence of elevated nitrogen and phosphorus levels that were lower than the manured sites. The importance of keeping good production records of cultural, nutrient and manure management practices are essential in providing information for relating residual nutrient levels to nutrient balances of applied organic and inorganic fertilizers.
The data showed that the variability in nitrate nitrogen and phosphorus status was greater between fields than within fields, particularly for nitrogen status whether the fields were manured or non-manured.
The highest concentrations of nitrogen and phosphorous were found at the soil surface (0-15 cm) with nutrient levels decreasing with depth. In some cases concentrations of nitrogen and phosphorus were observed below the 0 - 15 cm depth and in some cases they were not. Deep sampling also showed concentration of nutrients below 60 cm in some cases. As with any addition of nutrients there are potential risks to runoff and surface water contamination or leaching and groundwater contamination.
The method of sample collection did not affect the assessment of nitrate nitrogen and phosphorus status for fields. There was no difference in sampling accuracy between the analyses of fifteen individual samples for a field site and the analyses of the single composite of the fifteen individual samples. Nor were there any differences between the composite sample and the expert sampling method (four benchmark sample sites per field).
It was determined that a lesser number of samples is required for determining the nitrogen status than the phosphorus status for manured fields. As for non-manured locations generally a lesser number and the same number of samples were required for determining the nitrogen and phosphorus fertility status of fields.
Water table depths were found to vary more between locations than within each location. At the manured locations water table depths ranged from one to two feet to greater than nine feet. Depth to water table at the non-manured locations ranged from two to three feet to greater than nine feet from the ground surface.
The dominant grass forage species identified at the majority of the soil sampling sites were quack grass and poa with quack grass being more prevalent than poa at most field locations.