Detailed Steps for Establishing a Sugar Mandarin Nursery
1. Site selection
The nursery for sugar mandarin should be established on flat land, gentle slopes, or paddy fields with convenient irrigation and drainage that have convenient transportation, are far from pest and disease epidemic areas (at least 3000 m away from old citrus orchards and citrus huanglongbing orchards), are sheltered from the wind and facing the sun, have sufficient water sources, open terrain, deep topsoil, and a low groundwater table. It is best to choose paddy fields where no nursery stock has been grown in the previous crop or fields under paddy-upland rotation. When paddy fields are used as nursery sites, note that the groundwater table should not be too high; the groundwater table should be more than 50 cm below the ground surface. Loam, sandy loam with more organic matter, or red soil with high organic matter content and good irrigation conditions can also be selected for the nursery. Dry land with high, dry terrain and barren soil, sandy land, and low-lying, overly clayey land should not be used as a nursery.
2. Planning
A complete professional nursery consists of a mother plant garden, a propagation area, and a rotation area. The mother plant area (scion orchard) cultivates excellent varieties and provides scions of good varieties; the propagation area is the place for propagating nursery stock and can be divided into a sowing garden and a grafting garden. The former is used for sowing rootstock seeds and providing rootstock seedlings, while the latter is used for cultivating grafted seedlings. The area ratio of the former to the latter is 1:6; the rotation area is set up to overcome the drawbacks of continuous cropping and reduce pests and diseases. After 1-2 years of rotation (leguminous crops and vegetables are preferable for rotation), the nursery land can again be used as a sugar mandarin nursery. To save land, the sowing garden can also use corner plots in front of and behind houses for sowing and raising seedlings.
3. Land preparation
The nursery land should be plowed 1 month before sowing (deep plowing 25-30 cm) and sun-bleached white, then plowed and harrowed 2-3 times, leveled and finely harrowed, and weeds removed. During the last harrowing, broadcast per mu (mu is a unit formerly used to express area, now abolished and replaced by square meters, hectares, etc. 1 mu = 1/15 hectare = 666.7 sq m) 2000 kg of decomposed pig manure, cattle manure, or compost, 20 kg of superphosphate, and 50 kg of lime. To control underground pests, also broadcast 2 kg of 3% carbofuran granules. In the sowing garden, prepare seedbeds into beds with a surface width of 80-100 cm and a height of 20-25 cm; in the grafting garden, prepare seedbeds into beds with a width of 60-80 cm, a height of 20-30 cm (25-30 cm in low-lying land and paddy fields), and a ditch width of 40-50 cm. After the beds are made, rake the bed surface level and fine, then shallow furrows can be opened for sowing. To inhibit the growth of the main root of young seedlings, promote lateral root growth, and improve transplant survival rate, it is best during land preparation to lay plastic film at the bottom and pile fertile garden soil on top (15-20 cm high), using 5000 kg of fertile soil and 500-1000 kg of decomposed cattle manure and pig manure per mu, then mix thoroughly with the garden soil, and finally prepare the seedbed, after which shallow furrows can be opened for sowing.