“But Dr. Vœlcker,” said the Deacon, “states, and states truly, that ‘more leaves fall on the ground when clover is grown for seed, than when it is mown for hay; and, consequently, more nitrogen is left after clover-seed than after hay, which accounts for wheat yielding a better crop after clover-seed than after hay.’”
“This is all true,” said the Doctor, “but we can not accept Dr. Vœlcker’s analyses as proving it. To account in this way for the 1,375 lbs. of nitrogen, we should have to suppose that the clover-plants, in going to seed, shed one hundred tons of dry clover-leaves per acre! The truth of the matter seems to be, that the part of the field on which the clover was allowed to go to seed, was naturally much richer than the other part, and consequently produced a greater growth of clover and clover-roots.”
We can not find anything in these experiments tending to show that we can make land rich by growing clover and selling the crop. The analyses of the soil show that in the first eighteen inches of the surface-soil, there was 6,550 lbs. of nitrogen per acre, on one part of the field, and 10,300 lbs. on the other part. The clover did not create this nitrogen, or bring it from the atmosphere. The wheat with which the clover was seeded down, yielded 40 bushels per acre. If the field had been sown to wheat again, it probably would not have yielded over 25 bushels per acre—and that for want of available nitrogen. And yet the clover got nitrogen enough for over four tons of clover-hay; or as much nitrogen as a crop of wheat of 125 bushels per acre, and 7½ tons of straw would remove from the land.
Now what does this prove? There was, in 18 inches of the soil on the poorest part of the field, 6,550 lbs. of nitrogen per acre. A crop of wheat of 50 bushels per acre, and twice that weight of straw, would require about 92 lbs. of nitrogen. But the wheat can not get this amount from the soil, while the clover can get double the quantity. And the only explanation I can give, is, that the clover-roots can take up nitrogen from a weaker solution in the soil than wheat-roots can.
“These experiments of Dr. Vœlcker,” said I, “give me great encouragement. Here is a soil, ‘originally rather unproductive, but much improved by deep culture; by being smashed up into rough clods early in autumn, and by being exposed in this state to the crumbling effects of the air.’ It now produces 40 bushels of wheat per acre, and part of the field yielded three tons of clover-hay, per acre, the first cutting, and 5½ bushels of clover-seed afterwards—and that in a very unfavorable season for clover-seed.”
You will find that the farmers in England do not expect to make their land rich, by growing clover and selling the produce. After they have got their land rich, by good cultivation, and the liberal use of animal and artificial manures, they may expect a good crop of wheat from the roots of the clover. But they take good care to feed out the clover itself on the farm, in connection with turnips and oil-cake, and thus make rich manure.
And so it is in this country. Much as we hear about the value of clover for manure, even those who extol it the highest do not depend upon it alone for bringing up and maintaining the fertility of their farms. The men who raise the largest crops and make the most money by farming, do not sell clover-hay. They do not look to the roots of the clover for making a poor soil rich. They are, to a man, good cultivators. They work their land thoroughly and kill the weeds. They keep good stock, and feed liberally, and make good manure. They use lime, ashes, and plaster, and are glad to draw manure from the cities and villages, and muck from the swamps, and not a few of them buy artificial manures. In the hands of such farmers, clover is a grand renovating crop. It gathers up the fertility of the soil, and the roots alone of a large crop, often furnish food enough for a good crop of corn, potatoes, or wheat. But if your land was not in good heart to start with, you would not get the large crop of clover; and if you depend on the clover-roots alone, the time is not far distant when your large crops of clover will be things of the past.