Are you farming for the short or the long term?

Monday, December 6, 2010

Maintaining the long-term productivity of the soil means adding management activities that may have little, if any, short-term economic advantage

by KEITH REID

Managing a farm, like any business, is always a balance between generating enough cash to pay the bills in the short term, and investing in building the long-term value of your business. Problems arise when this balance gets skewed one way or the other.

Unfortunately, the advice that farmers receive from industry and from government is often slanted towards maximizing short-term profitability. This may be a response to low market returns, or simply a reflection that the negative impacts do not show for years or decades. The net result is decisions that appear to be economically rational, but that can cause environmental harm and may also, ironically, hurt the economic viability of the farm. 

The challenge, then, is to recognize the activities that have long-term consequences, either positive or negative, so we can take these into account in our decision-making. 

Long-term nutrient impacts. I find that most farmers recognize that decisions around phosphorus, potassium and lime have impacts beyond the immediate cropping season.  We would generally agree that the only time it makes sense to "mine" the nutrients out of the soil is where the field is scheduled to become a subdivision and future productivity is of no concern.

Problems do arise, however, in situations where there are too many nutrients in the form of livestock manure. Continual application of more nutrients than the crop can take out is going to build up soil fertility far beyond what crops need, creating the risk for losses to the environment or poor crop growth from nutrient imbalances.Soil physical manipulation of the soil. Short-term decisions are much more common when it comes to the physical condition of the soil, since any yield benefits always accrue to the current crops, while any negative effects don't show up until some future crop.

An easy example would be the decision to harvest a crop when the soil conditions are too wet, causing compaction. The short-term economic advantage is obvious, particularly if it is already late in the season. Harvest, and you get 100 per cent of the yield, or wait and potentially get none.

The long-term cost is less certain. If the weather co-operates next year, the yield impact might be small, or the winter freeze-thaw cycles might break up the compaction. Or the soil might be damaged badly enough to reduce crop yields for many years. This uncertainty makes it extremely difficult to put a precise "future value" on the soil compaction, but it is clear that there is a significant risk that the cost is going to be high. 

A wise farmer will mitigate that risk by reducing equipment weight and tire pressure, and by controlling the area that receives traffic to minimize the damage. Past actions to increase soil organic matter and improve soil structure will increase the resiliency of the soil, so that it is less affected by the occasional insult.

The impact of tillage is more subtle. In general, tillage accelerates the breakdown of soil organic matter and exposes the soil to increased erosion by wind and water. But the rate of these processes varies greatly with soil type and topography, and with the amount and intensity of tillage.

The result is a boost in the yield of the crop planted after tillage, but at the expense of the long-term productivity of the soil. This decline will be tiny in most soils, but there are examples of intensive tillage on highly erodible soils where the productive soil can literally disappear within a few years.

Ironically, as soil structure and organic matter decline from excessive tillage, the yield response to tillage increases since an untilled soil won't have adequate pore space to allow good root growth, leading to a "tillage addiction" that can be as damaging to the soil as a nicotine addition can be to your health.

Maintaining the long-term productivity of the soil means adding management activities that may have little, if any, short-term economic advantage. Reducing the frequency and intensity of tillage to the minimum required for crop production is a first step, and can show some immediate savings in fuel use.

Forage based rotations have long been recognized for their soil quality benefits, but are hard to justify when there aren't livestock to feed the hay to. Cover crops, or perennial forages for biomass, can help to fill this niche. The benefits won't necessarily show up in the "cash" row of the ledger, but they will eventually show up in better productivity of your farmland. BF

Keith Reid is soil fertility specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs, based in Stratford. Email: keith.reid@ontario.ca