Increasing Crop Water Use Efficiency in Advanced No-Till Systems
A winter pulse agronomy study was conducted at Amsterdam, MT, in 2002 and 2003. The first study examines optimal seeding rates for winter lentil and pea when sown mid-September in tall wheat stubble. The second study compares the response of winter lentil and pea to fall seeding dates and stubble height, using high yielding spring cultivars as the performance controls. The climatic patterns for both years were representative of terminal summer drought hitting in early July, typical for this region. In 2002, record setting heat occurred during the first half of July followed by temperature moderation in the last half, impacting early flowering treatments the greatest. In 2003, the onset of drought was more gradual, theoretically permitting earlier flowering treatments to minimize the drought effects.
Seeding Rate Study
For both winter lentil and pea, the best seeding rate was 50% greater than the recommended seeding rate for spring types (Table 1). This was due to plant mortality over winter and in early spring. No important relationships with plant height or seed size were observed in 2002.
Stubble Height, Fall Seeding Date Study
The stubble height response varied between years. In 2002, seed yields were greater in the tall stubble, while the opposite occurred in 2003. Temperatures were unusually cold in October 2002 and April 2003, and the short stubble treatment provided warmer soil temperatures that promoted timely growth of winter lentil and pea seedlings (Tables 2 and 3). Significant stand loss occurred for both winter lentil and pea in the tall stubble in 2003. Tall stubble increased plant height, which may improve harvestability of these low stature crops. Stubble height did not have a consistent effect on soil water extraction, however meteorological factors were affected. Wind speeds were reduced within the tall stubble canopy, but that did not translate into a significant increase in water use efficiency.
In 2002, delayed fall seeding delayed flowering and seed fill of winter lentil and pea until after the most severe drought in early July, allowing seed yields to equal those of the earlier date. However, in 2003, stand establishment was very poor for the delayed fall seeding which resulted in much lower grain yields. Consequently, we cannot recommend seeding winter lentil or pea later than mid-September.
For winter pea, the spring controls yielded equal to or greater than all fall seeding dates. For winter lentil, the spring controls yielded greater than all fall seeding dates in both years. This response was both unexpected and disappointing because our hypothesis was that early flowering winter lentil and pea would escape drought stress and therefore produce higher yields. Despite earlier flowering, and longer flowering periods with the winter pulses, there was no associated yield advantage. Small differences in soil water extraction were observed among the seeding date x cultivar treatments each year with no consistent patterns.
Tables have been provided as hard copies to SARE Western Regional Office. Contact Kristi Jensen.
1) Quantify effect of crop residue management on crop-available water, winter crop survival, and stubble microclimate effects.
2) Compare growth, productivity, and crop water-use-efficiency of spring vs. winter crop growth habits.
3) Extend new knowledge about residue management and crop rotations to farmers, industry reps, and research colleagues.
Second of three years complete and project is on time. Accomplishments to date can be highlighted as follows:
Bottom Line (Preliminary)
1) Seeding rates for winter lentil or pea should be 50% greater than that for spring types.
2) Seeding date should not be delayed past mid-September.
3) Yields of winter pea and lentil have been lower than or equal to spring controls.
Impacts and Contributions/Outcomes
Impact of this research is occurring in an unexpected manner. We demonstrated winter survival is reliable in our region, so long as optimal seeding date and rate are used. Although yield results have been disappointing there have been impacts in two unexpected ways. 1) There is a significant market for Austrian winter pea seed grown in Montana as a spring crop with low yield potential compared with spring cultivars, and several producers are now experimenting with fall seeding to increase yield of Austrian winter pea. 2) This research has been presented in front of numerous farmer and agronomic professional audiences, who have seen the early growth of winter pea as a strong fit for annual pea forage production in wheat-based systems.
New research proposals have been formulated to address both these issues. So in the typical sense for productive research, this current project has raised more questions than it’s answered.