In late spring, grasses begin to form seed and their chemical composition changes.  With the emergence of the seed stalk, nitrogen content drops markedly and the leaves become more fibrous, ligninous, and consequently, more reluctant to decompose.  At pollination ryegrass has dropped to about l percent nitrogen and by the time mature seed has developed, to about 0.75 percent.

These realities have profound implications for hay-making, for using grasses as green manures, and for evaluating the C/N of hay you may be planning to use in a compost heap.  In earlier times, making grass hay that would be nutritious enough to maintain the health of cattle required cutting the grass before, or just at, the first appearance of seed stalks.  Not only did early harvesting greatly reduce the bulk yield, it usually meant that without concern for cost or hours of labor the grass had to be painstakingly dried at a time of year when there were more frequent rains and lower temperatures.  In nineteenth-century England, drying grass was draped by hand over low hurdles, dotting each pasture with hundreds of small racks that shed water like thatched roofs and allowed air flow from below.  It is obvious to me where the sport of running hurdles came from; I envision energetic young countryfolk, pepped up on that rich spring milk and the first garden greens of the year, exuberantly racing each other across the just-mowed fields during haying season.

In more recent years, fresh wet spring grass was packed green into pits and made into silage where a controlled anaerobic fermentation retained its nutritional content much like sauerkraut keeps cabbage.  Silage makes drying unnecessary.  These days, farm labor is expensive and tractors are relatively inexpensive.  It seems that grass hay must be cut later when the weather is more stable, economically dried on the ground, prevented from molding by frequent raking, and then baled mechanically.

In regions enjoying relatively rainless springs or where agriculture depends on irrigation, this system may result in quality hay.  But most modern farmers must supplement the low-quality hay with oil cakes or other concentrates.  Where I live, springs are cool and damp and the weather may not stabilize until mid-June.  By this date grass seed is already formed and beginning to dry down.  This means our local grass hay is very low in protein, has a high C/N, and is very woody—­little better than wheat straw.  Pity the poor horses and cattle that must try to extract enough nutrition from this stuff.

Western Oregon weather conditions also mean that farmers often end up with rain-spoiled hay they are happy to sell cheaply.  Many years I’ve made huge compost piles largely from this kind of hay.  One serious liability from cutting grass hay late is that it will contain viable seeds.  If the composting process does not thoroughly heat all of these seeds, the compost will sprout grass all over the garden.  One last difficulty with poor quality grass hay:  the tough, woody stems are reluctant to absorb moisture.