Special calcium silicon-rich controlled release fertilizer for southern paddy rice and preparation method thereof

The invention discloses a special calcium silicon-rich controlled release fertilizer for southern paddy rice and a preparation method thereof. The calcium silicon-rich controlled release fertilizer is made from the following raw materials in parts by weight: 50-70 parts of a 5% special calcium silicate coated compound fertilizer for paddy rice, 10-30 parts of a 8% special calcium silicate coated compound fertilizer for paddy rice, 20-40 parts of a special compound fertilizer for paddy rice and 1-3 parts of zinc sulfate. The 5% special calcium silicate coated compound fertilizer for paddy rice and the 8% special calcium silicate coated compound fertilizer for paddy rice respectively mean that mass of calcium silicate coated layers account for 5% and 8% of total mass. Contents of nitrogen, phosphorous and potassium in the special compound fertilizer for paddy rice are 18%, 8% and 20% respectively. In the controlled release fertilizer, nutrients are regularly released, which is identical with nutrient absorption rules of southern paddy rice; membrane materials are cheap and available, do not have degradation problem and are environment-friendly. The controlled release fertilizer is once applied before transplanting paddy rice, an additional fertilizer is no longer required, and application amount of the controlled release fertilizer is reduced by 20% of that of common fertilizers, thus reducing labor intensity and fertilizer fund input of farmers.