Asparagus (Asparagus officinalis L.)
French: Asperge; Spanish: Espárrago; Italian: Asparago; German: Spargel| Vegetables, general crop data |
The crop, propagated by seed or crown, can be exploited for eight to ten years or more (up to 15 years). Tolerates extreme climatic conditions, but requires at least 12 °C in the soil with an optimum near 25 °C to produce shoots.
First picking should be delayed till the third year after planting. The yield reaches the maximum (6-8 t/ha) around the sixth year.
Plant density: 1 up to 4 plants/m2. Requires carefully prepared, sandy soil, rather neutral or slightly alkaline, deep and rich in organic matter.
Nutritional requirements increase after the turions picking; i.e. during maximum growth of the epigeous part of the plant.
Before planting: 30-40 t/ha organic matter, 150-200 kg/ha P2O5 and 200-300 kg/ha K2O; applied in bands at bottom of planting furrow.
During first year: 50-100 kg/ha N split during spring and summer season.
Following years: (kg/ha) N: 100-150; P2O5: 100-150; K2O: 150-200.
If available, also manure. The P2O5 is to be applied before winter, N and K2O in two or three doses in summer.
N in nitrate form preferred; K2O as potassium chloride (sulphate form could increase the bitter taste of turions).
During the long growing cycle Ca availability in the soil should be increased; a high Ca:P-ratio is important for yielding purposes.
Asparagus might require applications of Mg and B.
Under Tropical/Subtropical Conditions
Perennial. Harvested part: young shoots. Direct seeded and crown transplanting. Plant density: 15 000 to 25 500 plants per ha. Preferably grown in muck and light sandy soils well supplied with organic matter and pH range of 6.7 - 7.5. Does not tolerate acid soils but grows well in slightly alkaline and saline soils.
Target marketable yields in intensive commercial production = 1.5 - 4 t/ha.
Plant analysis data
P contributes to the improvement of spear quality, flavour, and texture, while K increases resistance to rust and helps maintain shoot quality. Mg is needed for carbohydrate storage. The crop also responds to B when soil supplies are deficient. Root inoculation with Glomus fasciculatum vesicular-arbuscular mycorrhizal fungus improves growth by improving P uptake and by decreasing the effects of Fusarium spp. diseases.
For the first year of establishment in the field apply all N, P and K before planting and field preparation. Annual treatments after field establishment should consist of split N applications, one-half before cutting begins and the remainder after harvesting has ended.
Present fertilizer practices
During the first year of growth for field establishment in sandy soils of semi-arid areas, 15 t/ha organic manure and 40 kg/ha N, 180 kg/ha P2O5, and 90 kg/ha K2O are broadcast before planting. Annually sidedress all organic manure, P and K before earthing up. The annual N applications are split in two, one-half applied after earthing up and the rest after harvest.
Before field preparation on mineral soils apply 110 kg/ha N, 130 kg/ha P2O5, and 130 kg/h K2O; thereafter annually 110 kg/ha of N after the cutting season has ended.
In northern areas (for yields of 7- 10 t/ha): in winter, 50 kg/ha N, 50 kg/ha P2O5 and 50 kg/ha K2O and in summer a further 50 kg/ha N. In southern areas rates are doubled.
KRARUP, A.; KRARUP, C.: Asparagus production in Chile. Acta Hort. 271, 253-256 (1990)SIMS, W.L.; SOUTHER, F.D.; MULLEN, R.J.: Growing asparagus in California. Coop. Ext. Univ. Calif. Lf. 21447 (1988)
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