"How can the good bacteria be encouraged to grow, and the bad ones prevented from forming? The necessary conditions for the growth of good bacteria are air, water, darkness, humus matter and freedom from acid condition of the soil. If the soil is acid then these other 'chaps' set up their work; so we must see to it that our soils are well cultivated, well aired, have plenty of manure, and, if acid, have a liming, so that these bacteria missionaries can start their good work. "The manure I spoke of above is the great source of nitrogen upon which most plants depend. There is nitrogen sufficient right in the air, but that again is not available. Certain plants like beans, peas and clovers belonging to the family of legumes are a great deal more fortunate than the rest of the plant families, for, under favourable conditions, they develop bacteria which make it possible to take into themselves free nitrogen. Just look here! See this narrow box; I can drop down one side of it. Here is a sheet of glass put on so you may look at the roots of the beans which are planted close to this glass side. Just observe the great extent of root system. Now see on the roots these white lumps, or nodules as they are called. These contain nitrogen-gathering bacteria. Some farmers in order to get more available nitrogen in the soil plant a crop of some legume. Then these root masses with their treasures on them are spaded into the soil. "But most plants depend for nitrogen on manure. Whenever you see sickly looking foliage know that nitrogen is lacking, and supply manure in order to obtain it. "The next element is potash. Its most common source of supply is wood ashes, not coal ashes. One may buy potash in the form of the muriate or sulphate. I told the boys before that potash was good for seed and fruit. Pretty necessary to have in the soil, is it not? Stunted fruit and poor seed mean lack of potash. Phosphorus helps in this work too, and also assists in the forming of fine flowers. Bone ash and phosphates are the sources of this food element. "So if we just consider the classes of soils with which we have to deal, remember the foods that must be had, and the effects on plants where one (or all) of these is lacking, we have in our hands a help to soil troubles. "Take sandy soil--what is its greatest need? I should say humus. It certainly should have more nitrogen. So add humus in the form of manure. Spread it on your piece of garden plot anywhere from two to six inches deep. This spaded in will, I think, do the work. You see sand allows water to trickle away too fast. Water must be held properly in the soil.