Sand Culture Vegetable Growing Techniques: Common Nutrient Film and Water-Vapor Sand Culture Methods

AbstractNutrient film sand culture: grow in raised beds, dig a trench in the middle of the bed bottom, then install pipes for drainage and place a nutrient solution storage tank, irrigate with a micro pump. Water-vapor sand culture: use a trough-shaped structure, build the upper layer with a "two-four wall" (24 cm thick) and the lower layer with a "three-seven wall" (37 cm thick), stack with galvanized iron mesh; its advantages are that the nutrient solution can be recycled during irrigation and is supplied directly to the roots, promoting root growth.

Everyone knows that the development of soilless cultivation technology has broken regional restrictions while also helping to improve crop growth quality and save and increase water; it is an emerging technology that is still developing. Sand culture technology is a further research result built on soilless cultivation. Its advantages are not only low growing costs and ease of popularization in a wide range of areas, but also very good yield and returns. Experiments show that using sand culture technology to grow cucumbers, for example, gives a yield of 25,000 kg per mu, an increase of 47.2%-93.1%. Below we will look at two common sand culture vegetable growing methods.

1. Nutrient Film Sand Culture

1. Form and nutrient supply equipment

(1) Sand culture bed form

Sand culture uses a raised bed form for growing. First dig a bed 30 cm high and 90 cm wide, level it slightly, then dig a trench 3 cm high and 10 cm wide in the middle of the bottom. Place a pipe in the trench for drainage, lay a layer of plastic film along the bottom to prevent seepage, and press it down with stones or bricks. On the same side of the drainage pipe, use a tool to cut downward openings, cutting one about every 45 cm, with a length of about one third of the entire drainage pipe. After cutting the openings, lay a layer of coarse river sand at the bottom, about 5 cm is enough, and fill the rest with ordinary river sand until it reaches the same height as the sand culture bed. When the growing bed is long, the bottom river sand should be laid with a certain slope to facilitate future drainage; when the growing bed is short, it can be kept the same length as the drainage pipe.

(2) Nutrient supply equipment

Place a nutrient solution storage tank in the greenhouse corridor, and use a micro pump to pump the nutrient solution into the sand culture bed. The micro pump must be well filtered; the best effect is an outer filter made from nylon stockings. According to the length range of the sand culture bed, punch a hole about every 20 cm as a nutrient supply source. Thin tubes are helpful for irrigation in nutrient film sand culture.

2. Sand culture irrigation method

Sand culture nutrient solution can use analytical grade reagents, but to save costs, cheap fertilizer or industrial pure chemicals are generally used instead, and its composition is similar to standard nutrient solution. Usually, sand culture nutrient solution is calculated per cubic meter, at a price of about 2.51 yuan. The irrigation amount should be controlled until the liquid drains out. For irrigation frequency, irrigate once per day on sunny days, and do not irrigate on cloudy and rainy days. In summer when the temperature is high and nutrient water evaporates faster, or when crops need supply during the fruiting period, the number of irrigations can be appropriately increased depending on the situation.

2. Water-Vapor Sand Culture

1. Sand culture bed structure

(1) The sand culture bed structure of water-vapor sand culture is trough-shaped. The bottom must be pressed flat and covered with plastic film to prevent seepage. The upper three layers are built as a "two-four wall" (24 cm thick), and the lower three layers are built as a "three-seven wall" (37 cm thick).

(2) On the protruding part of the wall surface, set up a net, preferably galvanized iron mesh, lay a layer of nylon mesh gauze on the net, then lay 2-3 cm of coarse sand and 8-10 cm of river sand. Every 50 cm, build a brick pier in the middle of the bottom to support and fix the iron mesh.

(3) The irrigated nutrient solution should exceed the surface of the river sand. In the early stage, the liquid level should be about 4 cm from the iron mesh, and later it can be adjusted to 6-8 cm. Excess nutrient solution should be drained in time through a valve.

2. Advantages of water-vapor sand culture

(1) When water-vapor sand culture irrigates nutrient solution, the fast flow rate can bring back some air, and after irrigation it can circulate.

(2) The air layer separates the organic matter into three parts. Crop roots are respectively in the river sand layer, the air, and the nutrient solution. Crops exposed in the sand layer and in the air both have sufficient oxygen, directly supplying the roots in the nutrient solution at the bottom, promoting growth and preventing root rot.