Crops: The Lynch File - Why forage yields have not kept up

Sunday, January 10, 2010

Cost of harvesting and soil compaction are factors. And the yield potential of new varieties has not improved much in 30 years

by PAT LYNCH

Ontario forage yields have not kept pace with the other field crops. Current Ontario agriculture ministry statistics record Ontario's forage yields in the last few years as about 2.4 tonnes per acre. This has slipped by about 15 per cent from the early 1980s, when the recorded yield was close to three tonnes per acre.

Meanwhile, corn yields have gone from 94 bushels an acre in the early '80s to 140 bushels an acre today. This is a 40-50 per cent increase.

In the mid 1970s, there was a push to put emphasis on forages. Some of the Ontario Soil and Crop Improvement Association weighed yields were in excess of five tonnes per acre. I expect that now most good growers are getting five tonnes an acre. In the early '70s, top growers were getting 100 bushels an acre of corn. Now they are getting 200 bushels. Clearly, forage yields have not kept pace.

The reasons are various. The yield potential of new varieties has not improved much over the last 30 years. The field management of forages has changed somewhat. In the '70s, growers and agronomists were pushing for the highest yields. Sometimes the feed produced gave feeding problems in the barn. The folk in the barns listened to their nutritionist and changed the way they managed forages. The biggest change was to cut later, increase fibre and decrease protein. This later cutting meant going from a four-cut system to a three-cut system. The net result was lower yields.

Another big factor is the cost of harvesting. If you can get 85-90 per cent of your yield with three cuts instead of four, the cost per tonne of harvest is probably lower. Since we are not likely to reduce harvesting costs, this may be a limiting factor.

There is one thing you can do to increase yields and that is to add grass to the forage blend. In the 1970s, the highest yielding fields had a mix of alfalfa and orchard grass.

There has been very little breeding done to improve orchard grass. The way the licensing system works is that yield counts. To get high yield from orchard grass, it must flower early and get good second growth. For the highest yield in a grass legume mix, you want an orchard grass that flowers later. Later flowering means it will still have good feed quality at first cut time. To get an orchard grass that mixes well with alfalfa, you have to buy one of the older later flowering varieties. Not all seed companies will source these varieties.

This brings another point. Today's producers tend to purchase their alfalfa seed as an add-on to their corn seed. When the seed order is thrown together, the discount for all seed in enticing. I wonder if more time is spent on the price factor than the agronomic factors that produce the highest yields.

The last factor is compaction. Today's forage fields probably are compacted more than any other crop field. Heavy harvesting equipment covers the field 10-12 times before the field is worked. The results are not seen after alfalfa is plowed down because of the soil structure factor that alfalfa gives. However, I think that compaction is holding yields back.   

The above suggests why yields are poor. I normally do not like to write about an issue without having some solution. I have no solution for the low forage yields. However, if more recognize the fact that forage yields have not kept up, maybe we can find a solution. BF

Pat Lynch, CCA (ON,) is an agronomist for Cargill in Ontario.