After one of the most severe droughts on record, the temptation for some producers to bring out the cultivator and return to black summerfallow can be strong. In many areas of the southwest, we became accustomed to good moisture conditions more often than not during the 1990's. The drought in 2001 reminds us how quickly things can change in Saskatchewan. If we don't receive any amount of precipitation by spring, the temptation to pull out the cultivator will be overwhelming for some producers, especially those who may have just gotten into direct seeding or have been contemplating to start direct seeding in 2002. It is an easy temptation to fall back on.
Tillage is something most farmers are familiar with and it is often perceived as a low cost method of weed control, risk management, soil moisture storage, and in some cases, as a method of residue management. However, most producers involved with tillage significantly underestimate the cost of this practice. There are more costs than just the fuel used to summerfallow. With all the associated costs involved with summerfallowing, such as fuel, depreciation on the tractor and cultivator, parts, increased wear and tear and hours on the tractor, and lost opportunity costs with having land lying idle, it amounts to about $5.00/ac per tillage operation. The more the tillage operations, the higher that cost is.
Many conventional farmers have the opinion that chem-fallow is much more expensive than tillage. Although there are higher up-front costs such as herbicide costs, the fact is that one usually doesn't have to make nearly as many herbicide applications as the farmer will with tillage. In addition, a smaller tractor can be used on the sprayer and many more acres can be covered in a day. The overall fuel consumption will be less and the wear and tear on the tractor will be much less than that of one being used for tillage summerfallow.
Another cost rarely included with summerfallowing is its inherent high risk of erosion. Loss of topsoil due to erosion is most severe with tillage. In addition, erosion on summerfallow occurs all year round and is not restricted to the growing season (although this is certainly the time period where most of the erosion occurs). Just driving in the winter, one can readily observe soil-covered ditches downwind from a summerfallow field. Even with limited stubble, as is the case with much of the southwest this year, there is much lower risk of erosion on standing stubble and chem-fallowed fields. Even minimal stubble will trap more snow than summerfallow fields. In addition, chem-fallowed fields don't lose much soil moisture during the summer.
Although tillage will mineralize a percentage of the organic material in the soil to available nitrogen, each tillage operation loses soil moisture and releases carbon dioxide (CO2). Release of CO2, a greenhouse gas, will become an increasing concern with respect to Canada's commitments in reducing greenhouse emissions. Now that soil has been approved to be a soil carbon sink under the latest international agreement, reducing tillage will become more of an economic consideration with farmers.
Without rain at appropriate times during the growing season, any farming system will not produce much of a crop. If there is no snow this winter or early spring rain, there will essentially be no soil moisture recharge. Undoubtedly, the soil moisture levels under deep-rooted stubble crops, such as chickpeas, canola and mustard will be extremely dry. Timely rains will be essential for adequate establishment of crops seeded onto the stubble of all crops under such conditions. As such, direct seeding in the southwest is not without risk. However, if fallow is being considered for risk management, chem-fallow has many advantages over tillage fallow. Granted, protein levels of wheat under good moisture conditions often tend to be lower than wheat seeded on summerfallow or on the stubble of other crops (particularly pulse crops).
Practices like greenfallowing may rectify this problem and still store soil moisture. Greenfallowing is the practice of seeding an annual legume such as field peas, silage peas, Indian Head lentils or more recently, a chickling vetch like AC Greenfix. The crop is either sprayed out, tilled under or foraged for hay or silage before it has a chance to mature. As a direct seeder, I would prefer to see farmers either spray out the greenfallow crop or cut it for forage. This usually takes place no later than flowering to flat pod stage or it is done in early July. Greenfallowing has several desirable effects. It is seeded late, allowing for the majority of weeds to emerge before a burnoff application prior to seeding. The crop is taken off relatively early, allowing summer precipitation to recharge the soil nearly as much as chem-fallow or summerfallow. Being legumes, these greenfallow crops fix nitrogen so the cereal crop the following year will likely have a protein advantage over chem-fallow. However, if it is very dry at the time you would seed the greenfallow crop, you are likely better off chem-fallowing. Under such dry conditions, the establishment and growth of these crops will be poor. Chem-fallowing would, therefore, be a more cost-effective and practical option.
For 2001, protein levels of wheat were good on both summerfallow and chem-fallow. Several farmers have told me that their summerfallow yields were better than their neighbour's direct seeded fields. While this may well be true, one also has to ask how did that direct seeded field, with a diverse crop rotation perform over the last 10 years? I would bet that the direct seeded fields have performed as good or better than the conventionally tilled fields over that time period. Many of these conventional farmers forget about how their fields crusted badly after a rain or how large areas had to be re-seeded due to the shearing off of seedlings by moving soil.
This spring I observed a lot of summerfallow fields with poor crop establishment due to the very dry spring conditions, so it wasn't just crops on stubble that had problems this past season. Will fallow acres in the southwest go up in 2002? If it is a dry winter and spring, the answer is likely yes. However, don't assume that bringing out the cultivator again for black summerfallow will be the answer. Chem-fallow and greenfallow are better options for those wanting a certain amount of fallow for managing risk.