Project: MLMMI 00-02-16
Objective
Assess the concentration of available phosphorous in manured and non-manured fields.
Evaluate the variability in soil nitrate nitrogen and phosphate phosphorous levels in manured and non-manure fields.
Performer
Larry Slevinsky
DGH Engineering Ltd.
Details
Status: Completed
Started: 2001-01-03
Completed: 2001-10-02
Funding Partners: who have contributed to MLMMI in support of this project:
Manitoba Pork Council and industry groups - $55,710
Amount Funded: $55,710.00
Performer Funded: $0.00
Total Cost: $55,710.00
Activity
First Interim Report received April 30/01.
Final report due Sept. 3, 2001.
Extension to Oct. 5/01 granted.
Final report received Oct. 2/01
Summary
The application of crop nutrients to agricultural soils requires a determination of the existing nutrient status within the crop rooting zone, normally considered to be the top 60 cm. Nutrient levels within agricultural fields can vary considerably, both in area and vertically. In order to determine soil nutrient levels, many different sampling methodologies have been investigated by other researchers in the past.
This study was initiated to investigate the nutrient status of agricultural soils in Manitoba that have a history of manure applications and to compare these soils to those that have not received manure. Soils characterized as fine (clays), moderately fine (tills) and coarse (sands) were studied. The sampling locations would be considered representative of soil landscapes commonly referred to as the Red River - Osborne, Newdale, and Almasippi soils.
The variability in soil nitrate-nitrogen and phosphorous level was determined in a total of 27 fields, 80 acres in area. Six manured and three non-manured fields were investigated in each soil type.
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, two of the random sites to represent the whole field (benchmark sampling).
The study found that manured fields have different nitrate-nitrogen and phosphorous fertility levels than non-manured fields. In general, manured fields had higher levels of nutrients, an indication that they have historically received higher level of nutrient applications. This is in agreement with previous studies by DGH Engineering Ltd. The need is apparent to implement manure nutrient management plans, under the supervision of a professional agrologist, that closely match nutrient supply to crop requirements.
Nitrate-nitrogen and phosphorous levels varied considerably within each field. This variability was greater in manured fields than non-manured fields and at the soil surface (0 - 15 cm depth) as compared to the soil profile (0-60 cm). As a result, more samples were required to accurately determine soil nutrient status in manured fields, except for nitrate-nitrogen in clay soils. With the exception of tills, more samples are required to determine phosphorous than nitrate-nitrogen levels.
Phosphorous levels were higher in manured fields for all soil textures. The phosphorous in both manured and non-manured fields was concentrated at the soil surface.
Soil texture had an effect on fertility status. Clays had lower nitrate-nitrogen and higher phosphorous levels than tills and sands. Tills had higher nitrogen and lower phosphorous levels than sands.
Landscape position had relatively little impact on nutrient status. In undulating topography (tills), and only in non-manured fields, the lower slope positions contained less nitrate-nitrogen than the mid and upper slopes.
There was no difference in sampling accuracy between the analysis of fifteen individual samples and the analysis of a single composite sample from fifteen locations. The benchmark sampling method tended to produce different results at the soil profile depth (0 - 60 cm), particularly for phosphorous.