Specialty Crops and Direct Seeding

1 A.E. Slinkard, 2 G.P. Lafond, and P. Miller 3

1 Crop Development Centre, University of Saskatchewan, Saskatoon and

Agriculture and Agri-Food Canada 2, Indian Head, and 3 Swift Current, SK, respectively.

Many changes in crop production and soil management have occurred in western Canada over the past 25 years. The largest changes occurred as a result of a reduction in fallow acreage, which was very high in Saskatchewan. Fallow acreage peaked at 18.5 million acres in Saskatchewan in 1972 (ignoring the 24 million acres of the LIFT program in 1970) and dropped to some 12.5 million acres in 1994 (a 40% reduction). People like Don Rennie and organizations like the Saskatchewan Soil Conservation Association Inc. have long promoted practices such as reduced fallow and direct seeding as a means of making crop production more economic and more nearly sustainable.

Reduced fallow acreage has been associated with many other important changes in crop and soil management. Some changes have caused a reduction in fallow acreage and some have resulted from a reduction in fallow acreage:

1. Increased use of chem fallow,
2. Increased stubble seeding,
3. Increased rotation length,
4. Increased crop diversification
5. Increased production of specialty crops, and
6. Increased direct seeding.

This then leads directly into the topic of this presentation, "Specialty Crops and Direct Seeding".

The major specialty crops in western Canada are pea, lentil, mustard and canaryseed. Other specialty crops include sunflower, bean, chickpea, faba bean, coriander, caraway, fenugreek, anise, buckwheat and safflower. Sunflower, bean and buckwheat are warm season annuals and grow slowly when seeded into the cool seedbed that occurs under direct seeding. Coriander, caraway, anise, fenugreek and canaryseed have slow developing seedlings that develop even more slowly under the cool seedbed that occurs under direct seeding. Thus, the specialty crops that respond most favourably to direct seeding are pea, lentil, faba bean, chickpea, safflower and mustard.

Nearly four million acres (1.6 million ha) of pea, lentil, faba bean, chickpea, safflower and mustard were planted in western Canada in 1995 and the area will increase in subsequent years. These crops originated as winter annuals in southwest Asia and, as such, are adapted to the cool seedbed that occurs under direct seeding. In addition these six crops (except mustard) can tolerate early spring frosts (down to -4°C) with minimal damage. The pulse crops (pea, lentil, faba bean and chickpea) can survive even more severe frosts that kill the shoot by virtue of their having two vestigial nodes at or slightly below the soil surface. A frost severe enough to kill the shoot destroys apical dominance and initiates growth from dormant buds in the leaf axil of the uppermost surviving node. Thus, these cool season pulse crops are uniquely adapted to both early seeding and direct seeding as they can grow and survive under cool seedbed conditions. The only exception is the extra-large-seeded kabuli chickpea which has problems with low temperature imbibitional damage and resulting seed rot due to its large seed and thin seed coat. The small-seeded desi chickpea presents no problems when direct seeded.

Results of Direct Seeding of Specialty Crops

Various researchers in western Canada have studied the response of several specialty crops to direct seeding. Much of this research was done by Agriculture and Agri-Food Canada (AAFC) researchers at Indian Head and Swift Current, SK. The Crop Development Centre was involved only in a small way and I will try to summarize some of the results of these studies.

The first case of direct seeding of pulse crops in western Canada was with lentil at Portage la Prairie, MB in 1978 (Slinkard 1979). Only part of the cereal stubble field was cultivated before a rainy spell after which the farmer seeded the entire field. I harvested six paired plots of 2 m2

each along both sides of the boundary line separating the direct-seeded area from the pre-seeding tillage area. While this "strip plot" technique is not the best experimental design, it still enables the researcher to detect large differences due to treatments. In this case both treatments yielded essentially the same: 1635 kg/ha for the direct seeded lentils and 1611 kg/ha for the pre-seeding tillage lentils. My conclusion at that time was that, "zero till lentils can be grown successfully, provided volunteer cereals and weeds do not provide serious competition".

Unfortunately, no further research was conducted on direct seeding of pulse crops until Dr. Guy Lafond and associates, AAFC at Indian Head, compared the effect of direct seeding vs. one pre-seeding tillage on yield and other agronomic traits of pea starting in 1987. They also collected data on crop water use and water use efficiency (Lafond et al. 1992). After eight years they summarized their data. They found that direct seeding produced a higher yield than conventional tillage (one fall tillage and one pre-seeding tillage) and that minimum tillage (one pre-seeding tillage) was intermediate (Table 1). Tillage systems had no effect on water use efficiency, but crop water use under direct seeding was 33 mm greater than water use under conventional tillage and 13 mm greater than with one pre-seeding tillage. Thus, the higher yield under direct seeding was directly attributable to the greater amount of water available to the crop. In other words, pre-seeding tillage allowed the evaporative loss of between 13 and 33 mm of water. In a water short area such as much of western Canada, the extra water saved can often result in increased yield of peas, as well as other crops.

Perry Miller, AAFC at Swift Current, conducted a 4-year comparison of direct seeding vs. one pre-seeding tillage using six specialty crops at Assiniboia and Swift Current. He also included fallow and stubble treatments in combination with direct seeding vs. one pre-seeding tillage. When he combined the fallow plus stubble treatments, the direct seeding treatment yielded about the same as the pre-seeding tillage treatment (65 vs. 64% of the yield of wheat (Table 2). In this case peas actually yield 23% greater than wheat, while the other specialty crops yielded less than 65% of wheat.

When Miller's data are combined over direct seeding plus one pre-seeding tillage, the stubble treatments yielded 68% of wheat vs. 62% of wheat for the fallow treatments, in contrast to conventional wisdom which says that fallow treatments will outyield stubble treatments. Mustard on fallow did outyield mustard on stubble, when yield was expressed as percent of wheat yield. However, stubble yields of all other crops, and especially pea and lentil, were higher than fallow yields. This emphasizes the unique adaptation of pea and lentil as crops that do well on cereal stubble, especially so if they are direct seeded.

This unique adaptation is emphasized even further in a 2-year study at Saskatoon. Four specialty crops and wheat were direct seeded or seeded after one pre-seeding tillage on wheat stubble in 1994 and 1995. In this case both pea and lentil outyielded wheat (Table 4), possibly because this site is in the moist Dark Brown soil zone (cooler and moister than the Brown soil zone sites at Swift Current and Assiniboia). At Saskatoon direct seeding of pea, lentil and wheat resulted in higher yields of these respective crops seeded under a pre-seeding tillage treatment. However, for some reason the yield of mustard (1994 only) and chickpea (1994 and 1995) following a pre-seeding tillage was higher than the yield of these crops when direct seeded. The contrary response of chickpea, relative to pea and lentil, merits further study. Comparisons should be made between desi chickpea and kabuli chickpea because the latter suffers from low temperature imbibitional damage (Chenn et al. 1983) while the former does not. Unfortunately, data were not collected on crop water use at Swift Current, Assiniboia or Saskatoon, and so we cannot positively state that the higher yield from direct seeding was primarily due to the conservation of a few mm of available soil moisture that was likely lost with the pre-seeding tillage operation.

Summary and Conclusions

All three studies show that pea yielded better under direct seeding than when seeded following a pre-seeding tillage. Data from AAFC Indian Head indicated that the higher yield was due to the greater crop water use relative to the pre-seeding tillage operation which resulted in evaporative loss of between 13 and 33 mm of available soil moisture. Crop water use data were not available from the other two studies. Lentil yields also were higher from direct seeding at the two Brown soil sites and at the moist Dark Brown soil site.

Results with direct seeding of chickpea, mustard, flax, safflower and sunflower were not as decisive. However, in only one case (kabuli chickpea) was the yield of these crops markedly lower from direct seeding than when seeded following one pre-seeding tillage.

In conclusion, pea, lentil, chickpea, flax, mustard, safflower, and sunflower can be successfully grown under direct seeding with little or no yield reduction relative to seeding them following one pre-seeding tillage. In fact, pea and lentil apparently do better when direct seeded into cereal stubble than following a pre-seeding tillage.

Data were not collected on other specialty crops such as dry bean, coriander, caraway, anise, fenugreek or buckwheat, so no recommendations can be made on these crops. However, dry bean may present a problem, because it is a warm season annual as is subject to low temperature imbibitional damage and subsequent reduced emergence under cool soil temperatures.

References Cited

Chenn, T.H.H., S.D.K. Yamamoto, L.V. Gusta and A.E. Slinkard. 1983. Imbibitional chilling injury during chickpea germination. J. Amer. Soc. Hort. Sci. 108: 944-948.

Lafond, G.P., H. Loeppky and D.A. Derksen. 1992. The effects of tillage systems and crop rotations on soil water conservation, seeding establishment and crop yield. Can. J. Plant Sci. 72: 103-125.

Slinkard, A.E. 1979. Commercial production of lentils in western Canada. Annual Report, 1978-79. Canada Grains Council, Winnipeg. Pp. 17-18.

Table 1. The effect of tillage systems on available soil moisture, crop water use, water use efficiency and seed yield of peas planted on winter wheat stubble at Indian Head, 1987-94.

a Treatment comparisons with a common letter do not differ at the 0.05 level.

z ZT: direct seeded; MT: one pre-seeding tillage; CT: one fall tillage and one pre-seeding tillage.

Table 2. Effect of direct seeding vs. pre-seeding tillage on yield of six specialty crops relative to the yield of wheat (Mean of six site-years, Fallow plus stubble, Assiniboia and Swift current, 1992-95).

Table 3. Effect of stubble vs. fallow on yield of six specialty crops relative to the yield of wheat (Mean of six site-years, direct seeding + pre-seeding tillage, at Assiniboia and Swift Current, 1992-95).

* Significant difference at 3 of 6 site-years.

Table 4. Yield of various specialty crops on wheat stubble with direct seeding or one pre-seeding tillage at Saskatoon, 1994-95.