How to Use Biogas Fertilizer Reasonably in Citrus Planting
The biogas slurry and biogas residue produced after anaerobic fermentation in a biogas digester are a very good biological organic fertilizer, and are sterile, non-toxic and highly effective. Applied to fruit trees, they can improve quality and increase yield. The following technical recommendations are now proposed on how to reasonably use biogas fertilizer.
Choosing the application method of biogas fertilizer
In citrus fruit trees, biogas fertilizer is mainly applied as biogas residue used in winter as a base fertilizer and in summer as a fruit-swelling fertilizer. Biogas slurry is used as a root-zone topdressing and foliar fertilizer.
Reasonably use biogas fertilizer according to the phenological period of citrus fruit trees
1. From after fruit harvest to before bud break, in order to ensure normal growth of the fruit trees, safe overwintering of the leaves, and a bumper crop the following year, use 0.3% urea plus 50% biogas slurry plus 10 mg/kg of 2,4-D (1 g diluted in 100 kg water) as a foliar fertilizer and spray 1-2 times. Dig pits under the drip line of the fruit trees, and according to the size of the fruit trees apply 10-50 kg of decomposed biogas residue fertilizer plus 0.5-3 kg of calcium magnesium phosphate fertilizer plus 0.5-5 kg of bran fertilizer to the roots.
2. For promoting shoots. When the buds of each flush of spring shoots, summer shoots and autumn shoots grow to the size of mung beans and before the leaves of the shoots unfold and turn green, apply an appropriate amount of decomposed bran water plus 5-50 kg of pure biogas slurry as a root-zone fertilizer, once every 15 days, for 3 consecutive applications. Use 0.2% urea plus 50% biogas slurry combined with insecticide and disease prevention spraying 2-3 times, which can clearly promote shoots, strengthen shoots, prevent insects and prevent disease.
3. For protecting flowers and fruits. From bud stage to before flowering of the fruit trees, in order to improve flower quality, apply 1-2 root applications of pure biogas slurry plus bran water fertilizer. Spray the foliage 2 times with 30% biogas slurry plus 0.2% borax plus 0.1% Lüwang No. 1. From after flower drop to before the end of physiological fruit drop, apply 2-3 root applications of pure biogas slurry plus bran water fertilizer, and spray the foliage 2-3 times with 30% biogas slurry plus 0.2% urea or plus 0.1% Lüwang No. 2, which can significantly increase the fruit-setting rate and increase yield.
4. During the fruit expansion period, the same as fertilization before bud break, apply biogas residue fertilizer to the roots once, and spray 50% biogas slurry fertilizer plus 0.3% potassium dihydrogen phosphate multiple times, which can effectively promote fruit expansion, increase sugar content, promote bright and glossy fruit coloration, and advance maturity.
Precautions for using biogas fertilizer
1. Biogas residue is best composted with calcium magnesium phosphate fertilizer and turf mud at a ratio of 10:1:10 plus an appropriate amount of bran fertilizer for 30-50 days and applied as a base fertilizer and fruit-swelling fertilizer.
2. When biogas slurry fertilizer is used as a foliar fertilizer mixed with pesticides for pest and disease control, a high concentration must not be used; 30%-50% is suitable, and the best spraying time is before 11 a.m. and after 3 p.m. on sunny days.
3. Biogas fertilizer must not be mixed with strongly alkaline substances, pesticides, etc., so as to avoid reducing fertilizer efficiency.