Soil improvement in citrus orchard establishment

Most of the soil in the citrus orchard needs to be improved, so that the soil layer becomes thicker, the soil quality becomes loose, the air permeability and aggregate structure become better, the soil physical and chemical properties are improved, the water absorption is increased, and the soil surface runoff is changed into subsurface flow, which plays the role of water conservation, soil conservation and fertilizer conservation.

Gardens with different site conditions have different key points for soil improvement: pollution-free citrus orchards in flat land and paddy fields, drainage ditches should be opened before soil improvement, groundwater level should be lowered and stagnant water should be eliminated. If the depth of the tillage layer is more than 0.5 meters, it can be dug to build borders for cultivation, and if the depth of the tillage layer is less than 0.5 meters, trenches shall be adopted to improve the soil. The key to the improvement of pollution-free Ponkan orchard in mountainous areas is to deepen the soil layer, conserve soil and water and increase fertility.

1. Paddy field improvement

Deep trenches can be used to build beds and trenches to improve soil.

(1) Deep trench: also known as border cultivation, suitable for fields (flat land) with a tillage layer depth of more than 0.5 meters. Dig a drainage ditch with a width of 0.7 to 1.0 meters, a bottom width of 0.2 to 0.3 meters and a depth of 0.8 to 1.0 meters every 9 to 9.3 meters, forming a planting border with a width of about 9 meters, and two rows of mandarins are planted on the border with a spacing of 2 meters.

For fields with poor drainage, dig a drainage ditch with an upper width of 0.7 to 1.0 meters, a bottom width of 0.2 to 0.3 meters and a depth of 0.8 to 1.0 meters every 4 to 4.3 meters in a row to form a planting border about 4 meters wide, and plant a row of Ponkan oranges in the middle of the border, with a distance of 2 to 3 meters.

(2) trench soil improvement: suitable for fields (flat land) where the depth of the tillage layer is less than 0.5 m. Each planting row of trench soil improvement digs a planting ditch with a width of 1 m and a depth of 0.8 m, and the bottom of the trench is dug down by 0.2 m (only loose soil, but not soil). Fill the ditch with 30kg of soil improvement materials such as weeds, crop straw, branches, farm manure and green manure per cubic meter (in terms of dry weight). If possible, mixed filling of soil and materials should be used as far as possible. The coarse soil modification materials are placed on the bottom layer and the fine ones are placed in the middle layer, with 0.15 to 0.20 meters per layer of fill. During backfilling, the original 0.6-0.8 m soil and coarse materials are mixed to a depth of 0.6-0.8 m; the original 0.2-0.4 m soil is backfilled to a depth of 0.4-0.6 m; the original 0.2-m topsoil is backfilled to a depth of 0.2-0.4 m; and the original 0.4-0.6 m soil is backfilled to a depth of 0.2-0.4 m. Finally, until the planting ditch is filled and 0.15 to 0.20 meters higher than the original site.

2. Improvement of dry land

The soil of dry sloping land is easy to impact and the water holding capacity is poor. Digging planting holes (pits) is used to improve the soil. The depth of the hole is 0.8-1.0 m and the diameter is 1.2-1.5 m. It is required that the planting hole does not have stagnant water. The planting holes of stagnant water should be drained by means of blasting, opening cracks between holes, or small drainage ditches at the bottom of the holes. When digging a planting hole, put the soil in the plough layer to one side and the raw soil to the other side.

The amount and method of organic fertilizer per cubic meter of planting hole backfilling is the same as that of trench soil improvement.