Impact of Cropping Sequence and Tillage System on Response to P Fertilization in Durum Wheat and Soybean

A study done to improve our ability to predict when P starter fertilizer is required by crops and identify management practices and fertilizer sources that may improve early season P availability to crops.


21 Mar 2006


Note: This study was initiated in 2004 with the establishment of the preceding crops. The first year of study of the P sources occurred in 2005.

Year 1:
Fields studies will be established at two locations near Brandon, varying in soil characteristics. The site will be set up as a randomised complete block, with a split plot layout.

Size: Plots of 2 M x 5 M should be laid out to allow a total of 6 treatments in each of the soybean and durum wheat crop to be grown in year 2, replicated four times in each tillage x preceding crop combination.
Soil Sampling: Take 1 to 2 samples per rep for site characterization in the fall. These should be 0-15, 15-30 and 30-60 cm.
Tillage: Reduced and conventional tillage. Tillage operations will be done in the fall and spring prior to seeding. Glyphosate applications should be used for control of weeds as needed in the fall and spring.
Crops: Barley, canola and flax
Fertility: 50 kg N ha-1 as urea and 20 kg phosphate ha-1 as MAP, side-banded. Keep samples of fertilizer for Cd analysis.
Production management: Standard management practices should be used to grow a “good” crop. Herbicide application should be as required for weed control. Seeding rate should be standard, recommended rates.
Residue Management: Residue should be cropped and returned to the same plots where it grew. Flax should be removed as is standard practice. Sampling:
a) Biomass samples should be taken at heading or early flowering if possible
b) At harvest, grain yield and residue yield should be measured. Samples of the straw and grain should be ground and submitted to the laboratory for analysis.

Year 2:
Soil Sampling: In the spring prior to seeding, soil samples should be taken in two locations (each end of each block) from 3 holes to make a composite sample at the 0-7.5, 7.5-15, 15-30 and 30-60cm depths.
Tillage: Tillage treatments should be maintained as in the preceding year.
Crops: Soybean cultivar – Gentleman at a seeding rate of 130 kg./ha
Wheat cultivar – AC Avonlea durum at a seeding rate of 120 kg./ha
Baseline Fertility: All wheat plots receive a total of 100 kg. N/ha as a sideband.
All Soybean plots receive approx. 7.5 kg. N/ha as a sideband to adjust for N applied in the MAP. Soybeans receive granular inoculum in the seed row.
Seeding date: Near mid-May
Herbicide treatments: As required for control of weeds, including fall and/or pre-plant glyphosate application.
Fungicide treatments: As required to control diseases.
a) Stand density should be measured 2 to 4 weeks after seeding.
b) Biomass sampling should be taken at heading or early flowering and a portion ground for analysis.
c) At harvest, grain yield and residue yield should be measured. Samples of the straw and grain should be ground and submitted to Eugene Gawalko at the Canadian Grain Commission laboratory for analysis for P, K, S, Ca, Mg, Cu, Fe, Mn, Zn, Cd and Se in the grain and P, Cd and Zn analysis of the residue. A second sample of the soybean seed should be sent to our laboratory for N analysis only. The durum wheat should be sampled for protein at Brandon, using NIR.
d) Microbiological measurements will be taken by U. of Manitoba.
Res_Cd. 2 Treatments:
  1. CONTROL (no P2O5)
  2. 30 kg. P2O5/ha as APP (10-34-0) Surface Dribble
  3. 30 kg. P2O5/ha as APP (10-34-0) Sideband
  4. 30 kg. P2O5/ha as MAP (11-52-0) Sideband
  5. 30 kg. P2O5/ha as AGRIUM CRP (10-51-0) Sideband
  6. 30 kg. P2O5/ha as AVAIL CRP (10-51-0) Sideband