Percolation of water, 41.

  Petals, 129.

  Petunia, 129.

  Pigweeds, 5, 6.

  Pistil, 130.
    function of, 131.

  Phosphate, odorless, 198.
    rock, 195.
    slag, 195, 198.

  Phosphoric acid, 195.
    available, 195, 196.
    in fertilizers, 195.
    in soil, 148.
    insoluble, 195, 196.
    reverted, 196.
    soluble, 196.
    sources of, 171.

  Phosphorus in plants, 66, 67.
    in soils, 68.

  Plank harrow, 102, 105.

  Plant, analysis of, 63.
    most important part of to plant itself, 7.
    most important part of to plant grower, 7.

  Plant diseases, 118.

  Plant food, 63.
    and the farmer, 5.

  Plant food, in soil, 63.
    in fertilizers, 68, 192, 205.
    what it is, 63, 69.

  Planting,
    corn, 84.
    grass seed, 84.
    grain seed, 84.
    method of, 83.
    seeds, 81.
    vegetable seeds, 84.

  Plants, 5.
    and the farmer, 5.
    conditions for growth, 6.
    composition of food of, 63.
    for study, 6.
    living, growing things, 6.
    parts of, 6.
    resemble one another, 6.
    why raised, 6.
    work of in making soils, 36.

  Plow beam, 93.
    coulter, 94.
    characteristics of, 95.
    clevis, 93.
    cutting roots, 15.
    draft ring, 93.
    handles, 93.
    jointer, 95.
    landside, 94.
    mouldboard, 94.
    parts of, 92.
    shackle, 93.
    share, 93.
    standard, 92.
    truck, 95.

  Plowing, 90.
    depth of, 96.
    effect on soil water, 156.
    favors root growth, 14.
    in fall, 99, 157.
    in spring, 98, 157.
    importance of deep, 15, 17.
    objects of, 91, 92.
    to save water, 92.
    time for, 98.

  Plows, 4.

  Plumule, 78.

  Pollen, 130.

  Pollination, 131, 132, 135.
    cross, 132, 133, 135.
    of wild goose plum, 134.

  Potash, 199.
    in fertilizers, 199.
    in soils, 149.
    sources of, 171.

  Potassium, in plants, 66, 67.
    in soils, 68.

  Potato, 6.
    soils, 28, 29, 161.

  Potato, sweet,
    roots of, 13.
    soils, 28, 160.

  Properties of a fertile soil, 141.

  Pruning, 137.

  Quitch-grass, 121.
    underground stem of, 121.

  Radicle, 78.

  Radish, shrunken root of, 10.

  Ragweed, 5.

  Rain, work of in making soils, 33.
    on clay soils, 41.
    on sandy soils, 41.

  Rake, 101.

  Rakes, 4.

  Raking and soil water, 158.

  Red spider, 117.

  Rhubarb soil, 28.

  Ridging the soil, 98, 158, 169.