Key Points of Rice Seedling Cultivation Techniques and a Detailed Explanation of Fertilizer Requirements
Rice is one of the most widely cultivated food crops in the world, and different classification methods can distinguish different varieties. With the development of cultivation techniques, rice is now grown more often using mechanized methods, which yield higher output and save more labor than manual planting. Today let us take a look at the key points of rice seedling cultivation and fertilizer requirements.
I. Key Points of Rice Seedling Cultivation
1. Selecting the site and making the bed
The seedling bed is best kept in one fixed location. Choose dry farmland with relatively high terrain, fertile soil and a sunny aspect. Apply organic fertilizer and grass peat as a top dressing to build up soil fertility and increase soil permeability. If conditions permit, plow the land in autumn and make the bed in autumn.
2. Treating the bed soil
In order to build up the fertility of the bed soil and meet the nutrients needed for seedling growth, it is best to apply 10 kg of high-quality sieved organic fertilizer per sq m. The organic fertilizer and a strong-seedling nutrient agent can be evenly mixed together into the seedling bed to a depth of about 10 cm. If the bed soil is on the alkaline side, it must be acidified, preferably to a pH of 4.5~5.5; the pH value had best not exceed 6, otherwise damping-off disease is likely to occur.
3. Seed selection, seed soaking and sprouting
Seed selection: the commonly used method is specific gravity selection, generally using 50 kg of water with 10~12 kg of salt or 20 kg of yellow mud. After thorough stirring, skim off the blighted and half-blighted grains floating on the surface, then rinse the selected seeds twice with clean water and soak them with a seed-soaking agent.
Seed soaking: the soaking time for rice is related to the water temperature maintained during soaking. At a water temperature of 20°C, soaking takes about 4~5 days; at 15°C, about 5~6 days; at 10°C, about 7~8 days. On the day before sowing, take the seeds out and dry them in the air.
Sprouting: where conditions allow, a sprouting machine can be chosen for sprouting, which makes temperature control and management easier. The sprouts produced should preferably be 1~2 mm long; they should not be too long and should be uniform. Farmers without a sprouting machine must pay close attention to temperature control when sprouting; the suitable temperature is 30~32°C, and one to two days is enough. It must not exceed 40°C, to prevent the sprouts from being damaged by high temperature.
4. Sowing
Sowing time: sowing can begin once the air temperature steadily passes 5~6°C. Different transplanting methods require different sowing rates.
II. Fertilizer Requirements of Rice
The entire growth process of rice is divided into the vegetative growth stage and the reproductive growth stage.
The vegetative growth stage is mainly the growth of the vegetative organs - roots, stems and leaves - and the accumulation of nutrients for reproductive growth. This stage is dominated by vigorous nitrogen uptake and assimilation, that is, mainly expansion-type metabolism. The goal of fertilization is to promote tillering, form strong seedlings, and ensure a sufficient number of panicles per unit area.
The reproductive growth stage is mainly the formation and growth of the reproductive organs and flowering and seed setting. In this stage, expansion-type metabolism gradually weakens while storage-type metabolism gradually strengthens to a vigorous level, that is, carbon assimilation predominates. Fertilization should center on promoting large panicles, more grains and plump grains. These two stages are interrelated; only on the basis of good vegetative growth can there be good reproductive growth. Therefore, only by understanding the growth and nutritional characteristics of each growth stage of rice and their relationship with the environment, and then fertilizing reasonably, can high yields be obtained.
The pattern of nitrogen, phosphorus and potassium uptake by rice at different growth stages is as follows: at the tillering stage, because the seedlings are small, the assimilating area of the rice plant is small and dry matter accumulation is relatively low, so the amount of nutrients absorbed is also relatively small. In this period, the nitrogen uptake rate accounts for about 30% of the total nitrogen uptake of the whole growth period, the phosphorus uptake rate is 16%~18%, and the potassium uptake rate is about 20%.
From young panicle differentiation to the heading stage of rice, the leaf area gradually increases and dry matter accumulation increases accordingly; this is the period of the greatest quantity and intensity of nutrient uptake in the whole life of the rice plant. The percentage of nitrogen, phosphorus and potassium nutrients absorbed in this period accounts for nearly half of the total nutrient uptake of the whole growth period of rice. After heading until maturity, because the absorption capacity of the root system weakens, the amount of nutrients absorbed decreases markedly: the N uptake rate is 16%~19%, the P2O5 uptake rate is 24%~36%, and the K2O uptake rate is 16%~27%.