On the water-solubility of plant minerals
Authors: Mäkelä Aarne , Kotilainen Kaija 
Published: July 2018

This paper deals with ash and mineral contents essential in the nutrition of livestock and man. The results of the investigated products are presented in Tables 1—3. Of the minerals the ash and the water-soluble part of it were determined, as well as the ash of the water-soluble fraction and the cations and anions P, Cl, K, Na, Ca and Mg. The determination of the water-solubility to some extent characterizes in what form the minerals occur in the plant. The following results were obtained in the determinations of the contents of total ash and the water-solubility. 1. As the Gramineae-grasses grow older the contents of ash and of individual minerals decrease, while the water-solubility simultaneously slightly declines (Table 1). The water-solubility of the ash and P is 70—80 %, that of K almost complete, that of Ca c. 50 % and that of Mg in general 60—70 %. 2. When red clover develops from the leaf stage to the blooming stage the contents of ash, N, P, Na, Ca and Mg decrease considerably, even to one half, while the content of K remains unchanged (Table 2). Simultaneously one can observe a decrease in the water-solubility. The water-solubility of the ash is 50—55 %, that of P 70—80 %, that of K almost complete, that of Ca 30—50 % and that of Mg 50—70 %. The contents of N, P and Ca in the leaves are considerably higher than in the stalks; at the blooming stage this is true also for Mg. On the other hand the content of K in the stalks is higher than in the leaves. The mineral content of the flowers is similar to that of the leaves, except that the content of ash is lower and that of phosphorus higher. 3. The water-solubility of the ash of cereal grains, cereal products and straws is 40—60 % (Table 2). The water-solubility of P in grains and wheat bran is c. 40 %, in brewers’ grains and straw 60—80 %. The water-solubility of K is only 60—80 %, except in straw where it is 90 %. The water-solubility of Ca in grains and brewers’ grains is c. 70 %, in the wheat bran and straw 30—40 %, in hulls of oats 20 % and awns of barley 66 %. The water-solubility of Mg in brewers’ grains is almost 70%, in oat grains and straw c. 50 %, in wheat grains and bran 20—30 %. 4. The water-solubility of the ash of roots and potato (Table 3) is high, 80—90 %. The ash content of tops and potato stalks is quite high, but the water-solubility of the ash only approximately 60 %. The water-solubility of P of the aforementioned plants and parts of plants is 70—90 % and that of K almost complete. The water-solubility of Ca in potato tubers, swede tops and spring rape is c. 50 %, where as it is low in other plants, especially in sugar beet tops and potato stalks. The water-solubility of Mg in potato tubers and tops is c. 70 %, whereas it is low in carrots, potato stalks and especially in swede roots. 5. In Table 3 are furthermore presented the mineral contents of some plants belonging to various groups of plants which to a limited extent may be used by some animals. The dandelion (Taraxacum officinale) is quite similar to the meadow fescue at the leaf stage with respect to its mineral content and the water-solubility of various minerals. The common sedge (Carex Goodenowii) is with respect to its mineral content and the water-solubility of the minerals similar to the blooming timothy, except; that the amount and water-solubility of P is low. The water-soluble ash and the contents and water-solubility of various minerals of water horsetail (Equisetum fluviatile) and common horsetail (E. arvense) are approximately the same as those of the meadow fescue at the leaf stage, except that the contents of Ca and Mg are higher and the water-solubility of Ca considerably less. The ash content of chickweed (Stellaria media) (c. 24 % in the dry matter) and of its specific minerals, the content of K (c. 10 %) is exceptionally high. On the other hand lichen (Cladonia alpestris) is especially poor in minerals.