Fertilization Technique Process for Soybean Plants

1. Introduction

Soybean plants are not picky about soil, the most suitable soil is one that has a deep cultivation layer, rich in organic matter, calcium, potassium, and has a neutral pH, good moisture retention, and good drainage. Soybeans are less tolerant to salinity and acidity than many other crops.

In the production of legumes in general and soybeans in particular, besides factors related to varieties, land, weather, and climate conditions, the technical aspect of fertilization for crops is decisive for the yield and quality of the product. Legume plants can self-supply most of the nitrogen they need during growth and development and provide a certain amount of fixed nitrogen to the soil system through symbiotic nitrogen fixation with Rhizobium bacteria. Crop diseases have caused significant damage in production, including wilt diseases caused by certain types of fungi such as Fusarium oxysporum; Sclerotium rolfsii, etc. These fungi persist long in the soil, plant residues and have been reported to harm many types of plants in the tomato and bean families around the world, causing serious damage to agricultural production and are very difficult to control with chemical pesticides. In light of this, there have been many studies on crop cultivation and selection, as well as the application of biological control measures by using microbial products, microbial organic fertilizers containing antagonistic microorganism strains capable of inhibiting and reducing the toxicity of these pathogenic fungi.

To achieve high yields and good quality in vegetable soybean crops, and to limit diseases such as plant wilt or certain root rot diseases (which chemical pesticides cannot prevent), farmers should use VN3 microbial organic fertilizer and SH01 organic fertilizer from Suối Hai Production and Trade Joint Stock Company for base and top dressing of the crops. VN3 microbial organic fertilizer, in addition to multi-nutrient, medium, and trace elements formed after the decomposition of pig and cow manure into humus, also contains beneficial microorganisms that promote plant growth and development and limit the growth of pathogenic microorganisms in the plant root zone.

The soil analysis results from the (Institute of Soil Science and Agrochemistry) for the soybean planting soil sample at Kênh Hữu, An Hoà Commune, Vĩnh Bảo District, Hai Phong city show:

• Soil pH: neutral, suitable for soybean cultivation; Total organic matter (OM): 2.12%, classified as nutrient-rich soil; Total nitrogen (N): 0.11% at an average level; Total phosphorus (P): 0.142% and available P: 16.40% at a rich level; poor Total potassium (K): 0.95% but available K: 35.39% at a rich level.
• Soil pathogen examination revealed the presence of nematodes causing root swelling and fungi such as Fusarium sp., Sclerotium sp. causing plant wilt. If soybeans are cultivated long-term without crop rotation and without seed treatment or soil disease treatment before planting, diseases may outbreak under favorable conditions, causing significant damage to crop yield.

2. Instructions for Using VN3 and SH01 Microbial Organic Fertilizers from Suối Hai Production and Trade Company

• Application: For soybean cultivation areas in Hai Phong and neighboring regions. Using VN3 microbial organic fertilizer and SH01 mineral organic fertilizer from Suối Hai Production and Trade Company helps save on the use of nitrogen, phosphorus, and potassium fertilizers by conventional methods, improves yield and quality of soybeans organically, and prevents plant wilt diseases, reducing disease incidence by over 60%.
• Dosage: Depends on the fertility of the soil. However, the recommended average dosage for 1 hectare of vegetable soybean cultivation is as follows:
  • 3,000 kg of VN3 microbial organic fertilizer
  • 1,000 kg of SH01 organic fertilizer (1)
  • 500 kg of SH01 organic fertilizer (2)
• Method of Application:
  Apply in two stages:
  • Stage 1, base dressing before planting: the entire amount of VN3 microbial organic fertilizer (3,000 kg) and SH01 organic fertilizer (1)(1,000 kg), lime can be added if the soil is acidic.
  • Stage 2, top dressing the entire amount of SH01 organic fertilizer (2)(500 kg) when the fruit begins to form.
• Some Notes:
  • For traditional soybean cultivation: VN3 microbial organic fertilizer and SH01 mineral organic fertilizer are used in the furrows before planting.
  • Once the plants grow, care for them to ensure good development. Water to maintain moisture, fertilize, hoe, and hill up the soybeans as per conventional methods.
  • Take care of the soybeans according to the recommended procedures.
  • Store the Fertilizer at room temperature, in a dry, cool place, not under direct sunlight or in places with temperatures >40C. The storage period is within 6 months from the date of manufacture.
  • Do not mix the Fertilizer with plant protection chemicals and individual chemical fertilizers when applying to crops.

3. Pest and Disease Control

Comprehensive and thorough pest and disease control measures must be applied. Soybean crops are susceptible to many diseases, such as rust, downy mildew, anthracnose, root collar rot, viruses, brown spot, seed decay, wilting… However, during this stage, the following diseases should be given special attention:

• Rust disease: Caused by the fungus Uromyces appendisculatus, it often severely affects leaves, stems, and fruits under high humidity conditions (above 90%), foggy weather, and lack of sunlight. The disease first appears on the older leaves close to the ground and then spreads to the upper leaves, causing pale yellow spots and gray spores on the underside of the leaves. If severe, the plant’s photosynthesis is poor, leading to a serious reduction in yield, even crop failure, with shriveled seeds and poor quality.
• Downy mildew: A common disease in many concentrated soybean growing areas. It mainly affects the leaves, causing them to yellow, dry, and fall off, leading to poor growth and development of the plant, reducing yield and seed quality.
• Anthracnose: Caused by the fungus Colletotrichum lindemuthianum, it affects the plant at all stages of growth, from germination to fruit formation. Dark brown or yellowish-brown sunken spots appear on leaves, leaf stalks, stems, fruits, and even seeds. The disease develops under saturated humidity conditions (95-100%) and temperatures of 16-120 degrees Celsius. If the humidity is below 80%, and the temperature is above 27 degrees Celsius or below 13 degrees Celsius, the disease will stop developing. The disease can mainly survive in seeds, on plant residues, and in the soil for 1-2 years.
• Bacterial leaf spot of soybean: Leaf spot disease caused by the bacteria Xanthomonas phaseolus and root spot disease caused by Pseudomonas glycine. The source of the disease from these two bacteria mainly exists on seeds and plant residues. The bacteria do not transmit through the soil as they quickly die in the soil once the residues have decomposed. Bacterial leaf spot disease thrives in hot and humid weather conditions. The optimal temperature for disease development is 26 – 30 degrees Celsius. The disease occurs in all soybean planting seasons, with varying degrees of infection in each season. In the spring and summer-autumn soybean crops, the disease often occurs and causes severe damage. In the winter soybean crop, the disease usually causes less damage. Most soybean varieties currently grown in production can be infected, with the disease tending to occur and cause severe damage on high-yielding domestic and hybrid soybean varieties (Vũ Triệu Mân, 2001).
• White mold root rot: The diseased plants wilt, appearing green or slightly yellow. The root collar and underground stem parts affected by the disease have brown spots, decay, and dry out. When uprooting the plant, the roots break off at the base, and a dense white fungal layer grows on the diseased stem base, spreading out over the soil surface, forming many round fungal sclerotia resembling white mustard seeds, later turning brown like tea seeds. The disease is caused by the fungus Sclerotium rolfsii. The disease develops strongly under relatively high temperatures, wet conditions, and poor plant growth. On monoculture sandy soils, the disease is more severe. On soils with a lot of organic matter and undecomposed plant residues, the disease is more damaging, with the spring crop being more affected than the autumn crop. The disease appears throughout the plant’s growth cycle. The fungus damages peanut tubers in the soil, causing them to shrivel, rot, mold, lose germination vigor, or when sown, the seedlings grow weak and become diseased. During the flowering and young fruit stages, the disease is more severe; the spring crop is more affected than the autumn crop.
• – Rhizoctonia root rot: Caused by the fungus Rhizoctonia solani. Initially, the disease appears as small spots on the roots, root collar, or the base near the ground, then spreads outwards. If favorable weather conditions occur, such as heavy rain or excessive irrigation combined with lush, dense, and closed plant canopies creating high humidity… the diseased areas (root collar, old roots, stem base…) will rot, turning dark black, waterlogged, or slightly dry (if the soil is dry and lacks water). This causes the plants to fall over, and when uprooted, the base breaks off, with the broken area rotting away. The leaves remain green, but the whole plant wilts.

In the chrysanthemum field, plants will be seen dying in clumps or patches, creating gaps and missing plants in the field. The disease in the chrysanthemum field may be due to over-irrigation, while the chrysanthemum plants have already formed canopies, with dense leaves that are not ventilated, creating wet conditions in the field. The disease-causing fungus survives long-term in the soil, can live saprophytically on plant residues for many years without dying. The disease often develops strongly under wet conditions (as mentioned above), with air temperatures around 22 – 28 degrees Celsius, on heavy clay soils, compact soils that easily form a crust after rain or irrigation, on waterlogged soils, and on soils specialized in cultivating chrysanthemums or some other host plants of the disease as mentioned above.

In addition, the phenomenon of root rot and root collar rot in the fields with many indistinguishable colors may also be caused by the fungus Rhizoctonia, and sometimes diseases caused by the fungi Fusarium solanni, F. oxysporium affecting the stem base, causing wilting, yellowing leaves (known as yellow wilt).

Most of the disease-causing microorganisms mentioned above mainly have their source of infection in the soil, on plant residues, and in manure. The disease occurs and develops under relatively high temperatures, wet conditions, and poor plant growth. On monoculture sandy soils, the disease is relatively more severe. Specifically, the black mold and white mold root rot types also develop strongly on soils with a lot of organic matter and undecomposed residues. The disease appears throughout the plant’s growth cycle, but the degree of disease varies at each growth stage, and the types of wilt diseases that cause damage also vary. In the seedling branching stage, most plants are affected by black mold root rot and root collar rot, but during the budding flower and young tuber stages, the wilt disease is much more severe, mostly white mold root rot,
especially in the spring and autumn peanut crops, including diseases that affect other crops such as potatoes and tomatoes in the late autumn-winter and late spring seasons in the Northern Delta and Central regions (Thanh Hoá, Nghệ An).

Control Measures:
Effective integrated control measures must be considered, such as planting disease-resistant varieties, crop rotation with other plant families, removing all plant residues after harvest; balanced and timely fertilization, weed control, hoeing, breaking the crust, ensuring drainage ditches are clear to avoid waterlogging after rain or irrigation to reduce soil moisture, and treating seeds with fungicides before sowing; applying biological products and organic fertilizers containing antagonistic microorganisms to prevent diseases originating from the soil.