Annual crops for silage

Most silage on the prairies is made from annual crops, especially cereals. Producing annuals for silage is similar to producing them for commercial seed or grain except that crop inputs are directed to optimizing total dry matter yield.

Quality is similar between varieties of a crop species. The differences between similar crops, such as the various cereal crops, is less than that between very different crops such as cereals compared to legumes. Protein quality comparisons are:

• oats - 9% protein
• barley - 10% protein
• spring rye - 10% protein
• triticale - 10% protein
• sunflower - 12% protein
• field peas - 18% protein
• fababean - 20% protein

There can be variations in quality from year to year. In a four year comparison at the Lacombe Research Station for example, Grizzly oats showed crude protein percentages ranging from 7.1 to 9.3.

Cereal silage
Cereals are easily ensiled since water soluble carbohydrate levels are high, buffering capacity is low, and moisture content is easily controlled. Since quality, especially protein content, is relatively low, cereals should be harvested before they get too mature. The maximum total yield and total protein is obtained by harvesting at or before the soft dough stage, depending on the species. At this stage moisture content is usually about 65% so the crop should be ensiled very soon after swathing. For lengthening the period of harvest it is usually better to use high yielding varieties or species with varying maturity dates rather than to delay seeding with one variety. Using one variety seeded at various dates usually results in lower overall yields.

If feeding requirements indicate a need for higher protein than that provided by cereals in the soft dough stage, this may be obtained by harvesting at the late milk to early dough stage. This will mean that dry matter yield is much lower so the economics of using higher quality crops versus cutting later and providing protein supplements should be considered.

Barley is a high yielding cereal under irrigation in Alberta and Saskatchewan. It is also relatively high yielding for dryland production in Brown and Dark Brown soil areas provided there is adequate soil moisture. An assessment of stored soil moisture should be made in the spring before planting barley or other cereals for silage in the Brown soil area, since summer rainfall may not be adequate to meet the needs of the crop.

In the Black soil zone, barley has a lower dry matter yield than oats, except in the most southwesterly part of Alberta (Longview), where it yields more. Barley silage is higher in quality and this compensates for slightly lower yields. Barley is very responsive to intensive production and will give a relatively higher yield with increased fertilizer rates, etc. It is also used to some extent in Grey Wooded soil areas but lower yield and lack of adaptability to factors such as acidity and excessive soil moisture limit its usefulness in some places.

Barley is more tolerant of saline soils than other cereals. Barley yields 50% of normal on a soil with an electrical conductivity of about 8 to 9 mmhos/cm compared to wheat which gives 50% of normal yield at about 7 mmhos/cm. Barley is less tolerant of acid soils than oats. Barley is earlier maturing than other cereals and may be planted in May to early June in parkland and Peace River areas. In southern areas, the planting date is less critical, but early May seeding is still recommended. Early maturity does mean that barley is a good choice when very late seeding is necessary. For silage production, both two-row and six-row barley varieties should be seeded at 75-110 lb/ac (84-123 kg/ha). The higher rates are used with higher soil moisture conditions. As for grain,
high rates of fertilizer, especially nitrogen, are required for high silage yields. Barley has less lodging resistance than other cereals, except oats; although the use of high nitrogen fertilizer increases this problem. There are varietal differences in lodging resistance. Both rough and smooth awned types are satisfactory for silage making. Problems with lump jaw may occur if rough awned varieties are cut for silage close to full maturity.

Since barley is an early maturing crop with some drought tolerance, it has a low water requirement. In irrigated areas maximum silage yields can be obtained with a total of 15-16 in. (375-450 mm) of water. If 8 in. (200 mm) of moisture is available from soil storage and rainfall, then about 6-7 in. (150-175 mm) of irrigation water is required. Moisture stress at the time of tiller initiation and development will reduce yield. Water requirements are highest from the shot blade stage to the time of kernel formation. High soil moisture during the jointing and boot stages promotes vegetative growth but does increase lodging.

For ensiling with horizontal silos, harvest should be completed by the time the standing crop drops to 65% moisture since some moisture is lost during harvest. In central Alberta the moisture content of standing barley drops by about 1% per day. The 65% moisture level occurs about three weeks after heading, i.e., at the early dough stage.
 

H + 1 week is heading stage plus one week

Comparing total yield of standing cereals at 65% moisture instead of a maximum dry matter yield shows barley yield to be relatively higher. For example, at Lacombe at 65% moisture there was a slight yield advantage of barley over oats or triticale. Barley also has a higher percent digestibility than other cereals except wheat. Again Lacombe data showed barley had 63% digestibility at three weeks past heading compared with oats at 56% and triticale at 60%. For production rations, increased digestibility is associated with higher levels of dry matter intake when the percentage of digestible dry matter is below 70%.

Barley also has higher percent protein compared with other cereals at a similar stage of maturity. Higher protein content but lower yield can also be obtained by harvesting earlier. For example, research at Brooks indicated the highest protein content is attained from the boot-to-head-emerged-stage but yields are approximately one-half those at the dough stage. Barley grain contributes 40-45% of the tonnage of barley silage when cut at the mid-dough stage of development. For this reason, high grain yielding varieties generally produce high silage yields.