Insect enemies.— There are two very important insect enemies of clover seed, the clover flower midge (Dasyneura leguminicola) and the clover seed fly (Bruchophagus funebris). These insects are found all over the United States and Canada. The entire clover seed crop is sometimes destroyed by the flower midge alone. The remedy is to feed off or mow the first crop just before timothy heads out. Pasturing or clipping back in spring to delay bloom ing ten days is useful. The clover-seed fly is seldom noticed, though it causes enormous injury. It eats out the seed, leaving only the light shell, which in threshing is blown away, leaving no trace of the insect's work. No practicable remedy is known.
Literature.
The subject of red clover seed-production has not as yet been studied exhaustively, and the litera ture on the subject is very fragmentary and scattering. Consult Darwin, Cross- and Self-fer tilization in the Vegetable Kingdom ; A. D. Hop kins, The Flowering Habits and Fertilization of the Flowers of Red Clover, Proceedings Society Promotion of Agricultural Science, 1896 ; A. N. M'Alpine, Production of New Types of Clovers and Grasses, Transactions Highland Agricultural So ciety, Vol. 10, 1898, p. 135 ; Clover Farming, Henry Wallace, 1898 ; ('lovers and How to Grow Them, T. Shaw, 1906; Clover Seed and Methods of Testing for Percentage Germination, United States Department Agriculture, Farmers' Bulletin No. 123; Michigan Board of Agriculture Reports, 1879, 1881, 1886 ; United States Bureau Ento mology, Circular No. 69.
Clover : Its culture and uses. Figs. 342, 343.
For centuries, good farm practice has been based on the regular use of clovers in the rotation. Long before the scientist had found how clovers enriched soils the farmer had observed the fact and had founded his practice on it. There is no other means of so surely and cheaply enriching the soil for suc ceeding crops as the growing of leguminous crops, chief among which are the clovers.
The requirements of clovers are simple, and much alike for each kind. They feed actively on the mineral elements of the soil and revel in soils rich in potassium and phosphorus. They send their roots deep into the subsoil and find there much mineral wealth. On their rootlets develop tubercles filled with myriads of bacteria, which gather nitrogen from the soil-air and make it available to other plants on their death.
Soil requirements and preparation.
Clover thrives on sweet soils, that is, soils con taining much carbonate of lime. Good farming is
much dependent on limestone. Where soils are acid, agriculture and the growth of clovers decay. Where there is abundant lime in the soil, acidity does not occur. Many regions that once grew good clover will not grow it now, and when the soils are studied they are found to be acid, and yet these soils may overlie the solid limestone rock, only a few feet down. Whenever fragments of this rock are mixed through the soil, clovers will thrive.
There are other soils that never contained much lime, and that within recent years have become too acid to permit the growth of clovers. Liming is the first requisite to restore clovers to these lands. The safest form is the crushed or ground and unburned limestone. This is neutral, and it does not attack the humus nor set free nitrogen. Acids will attack it and be destroyed, and any residue will remain for future years. Carbonate of lime in ground form, unburned, may be applied in large quantities and at small expense , it is a permanent invest ment that should yield dividends for a long time. It is quite safe to use as much as three to eight tons of carbonate of lime to an acre of land, and much more has been applied without harm. Next in importance to lime for clovers is the supply of phosphorus. Clover demands an abundance of phosphorus. This may he applied in any form, either by the use of acidulated rock, by " floats" used in connection with stable manures, or by the use of bone-meal. If there is then present a normal amount of potash, the clover will thrive. For best results, however, there should be a certain amount of vegetable matter in the soil. Humus puts "life" into the soil, adds plant-food and enlivens the soil by letting in the air and by encouraging the earth worms ; it also introduces bacteria in great abun dance, and these may help the growth of the clover and add to the wealth of the soil.
The writer has in mind an old field from which clover had been long banished because of its poor condition. It was divided into two parts, both alike nriched with suitable mineral fertilizers. One-half was given no manure. the other half was given a very light covering of yard manure. Both were s to n.d clover. The result was striking. The gr octh of clover on the part given the little manure was several times as heavy as that on the unmanured part ; and the enrichment of the land by the aid of the clovers was proportionately greater where the heavy clover grew.