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.
The best way to simultaneously overcome all of these liabilities is first to permit the bales to thoroughly spoil and become moldy through and through before composting them. When I have a ton or two of spoiled hay bales around, I spread them out on the ground in a single layer and leave them in the rain for an entire winter. Doing this sprouts most of the grass seed within the bales, thoroughly moistens the hay, and initiates decomposition. Next summer I pick up this material, remove the baling twine, and mix it into compost piles with plenty of more nitrogenous stuff.
One last word about grass and how it works when green manuring. If a thick stand of grasses is tilled in during spring before seed formation begins, its high nitrogen content encourages rapid decomposition. Material containing 2 percent nitrogen and lacking a lot of tough fiber can be totally rotted and out of the way in two weeks, leaving the soil ready to plant. This variation on green manuring works like a charm.
However, if unsettled weather conditions prevent tillage until seed formation has begun, the grasses will contain much less nitrogen and will have developed a higher content of resistant lignins. If the soil does not become dry and large reserves of nitrogen are already waiting in the soil to balance the high C/N of mature grass, it may take only a month to decompose But there will be so much decomposition going on for the first few weeks that even seed germination is inhibited. Having to wait an unexpected month or six weeks after wet weather prevented forming an early seed bed may delay sowing for so long that the season is missed for the entire year. Obstacles like this must be kept in mind when considering using green manuring as a soil-building technique. Cutting the grass close to the soil line and composting the vegetation off the field eliminates this problem.
Hoof and horn meal. Did you know that animals construct their hooves and horns from compressed hair? The meal is similar in nutrient composition to blood meal, leather dust, feather meal, or meat meal (tankage). It is a powerful source of nitrogen with significant amounts of phosphorus. Like other slaughterhouse byproducts its high cost may make it impractical to use to adjust the C/N of compost piles. Seed meals or chicken manure (chickens are mainly fed seeds) have somewhat lower nitrogen contents than animal byproducts but their price per pound of actual nutrition is more reasonable. If hoof and horn meal is not dispersed through a pile it may draw flies and putrefy. I would prefer to use expensive slaughterhouse concentrates to blend into organic fertilizer mixes.
Juicer pulp: See Apple pomace.
Kelp meals from several countries are available in feed and grain stores and better garden centers, usually in 25 kg (55-pound) sacks ranging in cost from $20 to $50. Considering this spendy price, I consider using kelp meal more justifiable in complete organic fertilizer mixes as a source of trace minerals than as a composting supplement.