답토양(畓土壤)의 Ca, Mg 포화비(飽和比)가 수도(水稻)의 Ca, Mg, K의 흡수(吸收)에 미치는 영향(影響)

Study on the Influence of Ca and Mg Saturation Ratios of Soil on the Uptake of Ca, Mg, and K by Rice Plant

토양중(土壤中) Ca 및 Mg의 포화비(飽和比)가 상이(相異)하고 가리(加里) 시용량(施用量)이 상이(相異)할 경우 Ca, Mg및 K가 수도수량(水稻收量)에 미치는 영향(影響)을 밝히기 위하여 Ca 및 Mg의 포화비(飽和比)를 81:19, 70:30, 52:48, 45:55 및 31:69로 각각(各各) 조절(調節)한후 가리(加里)를 반당(反當) 9 및 18kg을 시용(施用)하고 진흥(振興)을 공시품종(供試品種)으로 pot 시험(試驗)을 하였는바 그 결과(結果)를 요약(要約)하면 다음과 같다. 1. 토양(土壤)의 Ca 포화비(飽和比) 혹(或)은 Mg 포화비(飽和比)가 높으면 토양용액중(土壤溶液中)의 Ca 농도(濃度) 혹(或)은 Mg의 포화비(飽和比)가 높아 Ca우점토양(優點土壤)에서는 Ca 흡수(吸收)가 많고 Mg 우점토양(優點土壤)에서는 Mg의 흡수(吸收)가 많다. 2. Ca 포화도(飽和度)가 Mg 포화비(飽和比)가 비슷한 경우 토양용액중(土壤溶液中)의 Mg 농도(濃度)가 상대적(相對的)으로 높아 식물체중(植物體中)의 Mg 농도(濃度)가 Ca 농도(濃度)보다 상대적(相對的)으로 높아지는 경향(傾向)이었다. 3. 토양용액중(土壤溶液中) K 농도(濃度)는 Mg 포화비(飽和比)가 높은 토양(土壤)에서는 낮은 경향(頃向)이며 이로 인(因)하여 식물체(植物體) 가리함량(加理含量)도 Mg 포화도(飽和度)가 높은 토양(土壤)에서 적었다. 4. 가리증시(加里增施)는 식물체중(植物體中) K 함량(含量)을 늘리며 Ca+Mg+K에 대(對)한 K의 비(比)를 높이는 결과(結果)로 나타나서 식물체내(植物體內) Ca 혹(或)은 Mg 비(比)를 저하(低下)시켰다. 그러나 그 영향(影響)의 정도(程度)는 Mg가 Ca에 비(比)하여 민감(敏感)하였다. 5. 수도수량(水稻收量) 면(面)에서 볼때 토양중(土壤中) Ca:Mg 포화비(飽和比)는 7:3 정도(程度)가 가장 알맞은 것으로 나타났다. 6. 식물체(植物體)에 의(依)한 K의 흡수(吸收)는 $AK^+/{\sqrt{A(Ca^{{+}{+}}+Mg^{{+}{+}})$에 의(依)해서 영향(影響)은 받으나 $AK^+$ (가리활성도(加里活性度)) 자체(自體)는 Ca:Mg 비(比)에 영향(影響)을 받았다. 즉 $Mg^{{+}{+}}$ 농도(濃度)가 상대적(相對的)으로 높을수록 $AK^+$ 값은 낮아졌다.

A pot experiment was conducted to investigate the influence of Ca and Mg saturation ratios of soil on the uptake of Ca, Mg and K by rice plant. A silty loam soil was treated with $CaCl_2$ and $MgCl_2$ to obtain different degrees of Ca and Mg saturation. The studied ranges of Ca and Mg saturation ratios were 81:19, 70:30, 52:48, 55:45, and 31:69 in terms of the ratio of exchangeable Ca and Mg. Two levels of K application (90kg/ha, and 180kg/10a as $K_2O$) were also included in this study. The significant observation were summarized as follows. 1. When the Ca saturation of soil was dominant over Mg, the soil solution contained more Ca than Mg and vice versa. These led to the higher uptake of Ca by rice plant in Ca dominant soils and higher uptake of Mg in Mg dominant soils. 2. When the Ca and Mg saturation ratio was about equal, more Mg was released to soil solution leading to higher concentration of Mg in rice plant compare to that of Ca. 3. A trend was observed that the concentration of K in soil solution was lower in Mg dominant soils than in Ca dominant soils. This also resulted in the depressed uptake of K by rice plant under Mg dominant system when compare to Ca dominant system. 4. The increase application of K led to the increase in relative concentration of K to (Ca+Mg+K), and to the depression of divalent uptake by rice plant. However, it was observed that the degree of depression in uptake divalent by K application was more sensitive in case of Mg than that of Ca. 5. When viewed from grain yield of rice, it is pointed out that the optimum range of Ca to Mg ratio in soil may fall in the vicinity of 7:3. 6. Although K uptake by rice plant was influenced by the term of $AK^+/{\sqrt{A(Ca^{{+}{+}}+Mg^{{+}{+}})$ in soil solution, $AK^+$ itself was affected by the ratios of Ca:Mg in soil, as it were $AK^+$ value was decreased in Mg dominant soil than in Ca.