Reducing the Amount of Base Fertilizer Applied to Greenhouse Vegetables Has Many Benefits
Reducing the Amount of Base Fertilizer Applied to Greenhouse Vegetables Is Good
First, a greenhouse is an enclosed facility, and harmful gases inside are not easily expelled. If too much base fertilizer is applied, more ammonia volatilizes, and the vegetables inside suffer ammonia damage, causing dry leaf edges or necrotic spots, and in severe cases the leaves wither, leading even to plant death.
Second, before vegetables enter the flowering and fruiting stage, their fertilizer uptake is only about 1/6 of the total uptake for the whole growth period. During this period, the soil should not contain too much fertilizer; too much not only causes fertilizer burn of the seedlings but also easily leads to excessive vegetative growth of the young plants, affecting flower bud differentiation and delaying the fruiting period.
Third, because greenhouse vegetables receive large amounts of fertilizer over a long period, the soil is not lacking in various nutrient elements; what it lacks is carbon dioxide. Crops need very little carbon dioxide during the seedling stage, and this demand gradually increases as the number of leaves increases, reaching a peak during the full fruiting stage. The carbon dioxide in a greenhouse comes mainly from the decomposition of organic fertilizer in the soil. After organic fertilizer is applied to the soil, the peak period of carbon dioxide release is roughly between 10 and 50 days after application. Applying large amounts of base fertilizer not only causes fertilizer burn of the seedlings, but also, because the crops use very little carbon dioxide in the early growth stage, most of the released carbon dioxide is wasted. After entering the fruiting stage, the demand for carbon dioxide increases, but by then the peak period of carbon dioxide release from the soil has already passed, so the carbon dioxide supply is insufficient, which restricts the performance of photosynthesis and affects the increase in yield.
Therefore, the amount of base fertilizer used should not be too much; generally, applying 2500-3000 kg of base fertilizer per mu is sufficient. Large amounts of organic fertilizer should be applied as top dressing in stages after flowering and fruiting, so as to provide a continuous, adequate supply of carbon dioxide for crop photosynthesis.
Second, before vegetables enter the flowering and fruiting stage, their fertilizer uptake is only about 1/6 of the total uptake for the whole growth period. During this period, the soil should not contain too much fertilizer; too much not only causes fertilizer burn of the seedlings but also easily leads to excessive vegetative growth of the young plants, affecting flower bud differentiation and delaying the fruiting period.
Third, because greenhouse vegetables receive large amounts of fertilizer over a long period, the soil is not lacking in various nutrient elements; what it lacks is carbon dioxide. Crops need very little carbon dioxide during the seedling stage, and this demand gradually increases as the number of leaves increases, reaching a peak during the full fruiting stage. The carbon dioxide in a greenhouse comes mainly from the decomposition of organic fertilizer in the soil. After organic fertilizer is applied to the soil, the peak period of carbon dioxide release is roughly between 10 and 50 days after application. Applying large amounts of base fertilizer not only causes fertilizer burn of the seedlings, but also, because the crops use very little carbon dioxide in the early growth stage, most of the released carbon dioxide is wasted. After entering the fruiting stage, the demand for carbon dioxide increases, but by then the peak period of carbon dioxide release from the soil has already passed, so the carbon dioxide supply is insufficient, which restricts the performance of photosynthesis and affects the increase in yield.
Therefore, the amount of base fertilizer used should not be too much; generally, applying 2500-3000 kg of base fertilizer per mu is sufficient. Large amounts of organic fertilizer should be applied as top dressing in stages after flowering and fruiting, so as to provide a continuous, adequate supply of carbon dioxide for crop photosynthesis.