Rock salt, 31.

  Rollers, 107.

  Rolling, 101, 106, 158.
    autumn-sown grain, 106.
    light soils, 106.
    reason for, 106.
    spring-sown grain, 106.

  Rolling cutter harrows, 102.

  Root, 8.
    how it takes moisture, 18.
    most important part of plant, 7.

  Root hairs, 17, 18.

  Roots,
    absorb water, 9, 11, 17.
    absorb plant food, 10, 11.
    alfalfa, 13.
    and fertilizers, 15.
    growth of in length, 16.
    conditions necessary for growth of, 8, 20, 141, 220.
    corn, 13.
    cowpea, 12.
    depth of growth of, 12.
    extent of growth of, 12.
    habit of growth of, 11, 15.
    hold plant in place, 9, 11, 15, 16.
    important lessons from, 13, 15.
    location of, 12, 13.
    need firm soil, 20, 22, 23.
    need mellow soil, 20, 22, 23.
    need moist soil, 20, 22, 23.
    need plant food in soil, 20, 22, 23.
    need warm soil, 20, 22, 23.
    need air in soil, 21, 22, 23.
    produce new plants, 10, 11.
    rapidity of growth of, 15.
    soy-bean, 12.
    store food, 10, 11.
    sweet potato, 13.
    tree, 13.
    uses of, 9, 10, 11, 15.
    work of, 9, 10, 15.

  Rotation of crops, 219.
    benefits from, 230.
    conditions which modify, 232.
    effect upon fertility, 224.
    examples of, 234.
    general rules for, 233.
    length of, 233.
    typical, 231.

  Sampling soils, 163.

  Sand, 26, 38. 
    Fresno, 28.
    grades of, 26. 
    Miami, 28. 
    Norfolk, 28.
    power to absorb water, 41, 43.

  Sandy soils, 27.
    adapted to early truck, 27.
    effect of humus on, 43, 44, 220.
    improving, 43.
    water-holding power of, 44.

  Sandy loam, 28.

  Sapwood, 126.

  Scythes, 4.

  Seed leaves, 77.

  Seed, 130.
    classification of, 85.
    crab,
    drills, 4, 84.
    planting, 81, 83.

  Seeds, 8.
    depth to plant, 81.
    how they come up, 77.
    how to test, 75.
    which germinate at a temperature of 45 degrees, 74.
    which germinate at a temperature of 60 degrees, 74.

  Seeds to germinate,
    need air, 72, 73, 75.
    need heat, 73, 75.
    need moisture, 71, 75.

  Sepals, 129.

  Shallow cultivation, 14, 15, 167, 169.

  Share of plow, 93.

  Shackle of plow, 93.

  Silt, 27, 38.

  Silt loam, 29.

  Small fruit soils, 20.

  Soil,
    a fertile, 141.
    definition of, 23.
    formation of, 30, 237.
    material composing, 147, 26.
    mulch, 56.
    temperature, 57, 60.
    testing, 162, 215.
    texture, 37, 142.
    texture important, 142, 143.
    ventilation, 68, 142.
    warmed by sun, 58.
    warmed by conduction, 58.
    water, 40, 151.