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CHAPTER IV.

THE FARMER'S INTEREST IN GOOD SEED, AND HOW TO TEST SEED

The farmer is especially interested in obtaining seed free from such noxious weeds as Canada thistle, quack grass and dodder. To avoid the introduction of such weeds, the seeds should be examined by the experiment station in the state in which the farmer is located or by the U. S. Dept. of Agriculture. It is customary in the seed laboratory to secure an average sample, thoroughly mixed, of the seed to be examined; then to weigh out 2 or 5 grams and separate out the impurities, such as weed seeds, dirt, chaff, etc. The remaining seed is then weighed and the amount of impurities determined. When a given quantity of weed seed is large this is weighed separately and the per cent of impurity obtained. A more accurate way is to use the table given below. This method is fairly accurate. We have for a number of years checked these results with those determined by weighing. If the weighing method is used, the analyst gives the total impurities and names those found.

The following table showing the number of seeds to the gram of various species of weed seeds was compiled by D. C. Snyder and Charlotte M. King in the Botanical Laboratory of the Iowa state college. To ascertain the number of seeds per pound in any given variety multiply the number per gram by 453.584.

NUMBER OF SEEDS TO THE GRAM IN WEED SEEDS FOUND AS IMPURITIES IN CLOVER SEED. PREPARED BY D. C. SNYDER AND C. M. KING

Abutilon Theophrasti (Velvet Leaf)

Acnida tuberculata (Water Hemp).

109

2,800

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Mr. J. R. Campbell has kindly worked out the following formula for determining the percentage of impurities in some of the different agricultural seeds. A table is herewith appended giving the number of seeds in one per cent of one teaspoonful or 5 grams of clover seed, and one per cent of one teaspoonful or 4 grams of timothy seed.

Analysis of Seed (Approximate).—In making an analysis of red clover or any other seed, the sample should be thoroughly mixed. If we have a sack of seed, a handful should be taken from the top, another from the middle, and another from the bottom of sack. Mix them in a pasteboard box, plate or anything handy; then take a pinch here and there until we have a slightly rounding teaspoonful. (Use common tin teaspoon.) Do not have it more than slightly rounding or the figures will be inac

curate.

Pour this out on a sheet of white paper, or glass, and with the aid of a toothpick, lead pencil or anything convenient, separate the good clover into one pile and the weed seed and dirt into another. Then with the help of the manual in identification, separate the different weed seeds and count them. Next find the percentages of each, using the table for this purpose. For example, suppose there are 120 seeds of crab grass and 16 seeds of buckhorn. The table says 182 seeds of crab grass are equal to I per cent. Therefore 120 seeds equal 120/182 of 1 per cent, or .659 per cent, and since 57 seeds of buckhorn equals 1 per cent, 16 seeds equal 167 of 1 per cent, or .28

I

per cent. The sum of both is .939 per cent, a little less than one per cent. The weight of the dirt will have to be guessed at, as it varies greatly with different kinds.

(The above method is for the use of those who have not the apparatus for an exact analysis. The results are, of course, only approximate, but are near enough for the purpose of the law.)

NUMBER OF SEEDS REQUIRED TO MAKE I PER CENT BY WEIGHT OF 5-GRAM SAMPLE (EQUAL TO ONE TEASPOONFUL OF seed)

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