The Effect of Tillage System and Proceeding Crop on Phosphorus Response of Flax

Assess the interactive effects of tillage system, preceeding crop and P management on flax production.

IPNI-1999-CAN-MB11

23 May 2001

2000


Summary
In 1999, seed yield of wheat and canola was similar under CT and NT; where differences exited, seed yield was higher under NT. In contrast, in 2000, seed yield was consistently higher under CT than NT. Differences may be due to delayed seeding in 1999 and cold, wet conditions throughout 2000. Reduced aeration under NT in 2000 may have reduced crop yield. There was no P by tillage interaction in either year, indicating that P response was similar under the two tillage systems.

Flax yield in 2000 was generally similar under NT and CT. Where differences existed, yield was higher under NT. The flax site was on a well-drained upper slope position which may have enhanced aeration. Seed yield of flax was higher when grown after wheat than after canola at both locations under both tillage systems. This may reflect early season weed competition from the volunteer canola. However, mycorrhizal effects may also have played a role. Samples have been taken for measurement of mycorrhizal colonization, but information is not available yet.

Seed yield of flax was not influenced by P application to the flax crop at either location. However, there was a tendency for seed yield to decrease with application of P to flax under NT at the Research Centre location. At the No-Till Farm location, P fertilization of the preceding crop led to higher flax seed yield the following year, with the effect being greater when wheat was the preceding crop as compared to canola. It may be a useful strategy for producers to increase P application in preceding crops, rather than fertilizer the flax crop, in order to increase P availability while eliminating the risk of seedling damage.

Yearly details
1999
Phosphorus fertilization increased biomass yield of canola at both locations and of wheat at the no-till farm. With canola, yield increased with increasing P level to 50 kg/ha at both locations, while with wheat, the yield increased only with the first 25kg/ha of P2O5. Tillage did not influence biomass yield of canola, but biomass yield of wheat at the no-till farm was higher with no-till than conventional till, in spite of the very wet and cold conditions experience during this summer. No tillage by P interactions occurred, indicating that P response patterns were similar under no-till and conventional till.

Seed yields were low, due to late seeding and adverse weather throughout the growing season.
Seed yield of canola was not significantly affected by P application or tillage system at the research centre site, but was increased by P application on the no-till farm site. Canola seed yield also tended to be higher with NT than CT at the no-till farm site, but there was no tillage by P interaction, indicating that the crop response to P was similar under the two tillage systems. Wheat grain yield tended to increase with P application on the research centre site (p<0.0780) and tended to be higher under NT than CT (p<0.0810), however on the no-till farm, there was no significant effect of either P or tillage on wheat grain yield.

2000 Canola and Wheat
Biomass yield of both wheat and canola at 5 weeks was higher under CT than NT at both research locations in 2000. This differs substantially from the results in 1999, where tillage system had little effect on biomass yield, and if differences occurred, yields were higher with NT than CT. In 1999, seeding was delayed substantially due to excess moisture. The late seeding may have led to generally warmer soil temperatures, favouring NT as compared to the early seeding conditions in 2000. Conditions throughout the summer in 2000 were wet and cold. Saturated conditions in the root zone may have led to poor aeration and restricted yield under NT, particularly on the Research Centre Farm, where NT systems were relatively newly established.

Phosphorus application increased biomass yield of canola on the No-till Farm, but not at the Research Centre Farm. Biomass yield of wheat was increased with P application at both locations. A P by Tillage interaction occurred for canola production at the No-till farm, where biomass yield increased with P application to a greater extent under CT than under NT.

Seed yield of both canola and wheat was higher under CT than NT, with the effect being greater on the Research Centre Farm than on the No-Till Farm. Seed yield was also increased with P fertilization on the No-Till Farm, but not at the Research Centre Farm. There were no differences in response to P application under the two tillage systems. Poor seed yield under NT may relate to the persistent wet conditions experienced in 2000.

2000 Flax - Residual Effects
Biomass yield
Flax biomass yield was consistently higher when grown on wheat stubble than on canola stubble. Part of the effect of preceding crop may be due to the high density of volunteer canola in the flax during early growth, as early season weed competition is particularly damaging in flax. Biomass yield was not significantly influenced by tillage system at the Research Centre Farm, but was increased by NT as compared to CT at the No-till Farm. The biomass yield increase due to NT was greater after canola than after wheat.

Phosphorus fertilization of the flax crop increased biomass yield under NT when grown on canola and under CT when grown on wheat at the Research Centre Farm. In contrast, on the No-till Farm, application of P fertilizer to the flax decreased biomass yield with all crop-tillage system combinations. There was no influence from the residual effect of P applications in the preceding crops on biomass yield of flax at either location.

Seed Yield
Seed yield of flax was higher when grown after wheat than after canola at both locations under both tillage systems. This may reflect early season weed competition from the volunteer canola. However, preliminary examination of mycorrhizal infection indicates higher mycorrhizal formation after wheat than canola, which may have enhanced P nutrition and crop yield. Seed yield tended to be higher under NT than CT at the No-Till Farm location, but was not significantly influenced by tillage system at the Research Centre location.

Seed yield of flax was not increased by P application to the flax crop at either location. However, there was a tendency for seed yield to decrease with application of P to flax under NT at the Research Centre location. Flax does not tend to proliferate roots in fertilizer reaction zones and so is relatively ineffective at absorbing P from fertilizer applications. At the No-Till Farm location, P fertilization of the preceding crop led to higher flax seed yield the following year, with the effect being greater when wheat was the preceding crop as compared to canola. Increased residual P from previous fertilizer applications may be as or more available to flax than side-banded P applications.