How Soil Mycorrhizal Fungi Improve Potato Root Health and Tuber Development

An often frustrating field problem for many potato growers is the good-looking green canopy coupled with correct application of fertilizers and yet poor yield, size or quality of the tubers. In most instances the problem isn't the best mycorrhizal fertilizer, it's simply too little. The actual issue lies beneath the ground where problematic root zone activity, low microbial soil health and nutrient immobilization limit the potato roots ability to easily tap into available nutrients. Of all nutrients phosphorus has one of the most important roles in the initiation of the t tubers, their root density, early plant growth and vigor. Excessive liming or fertilization only result in less and less being absorbed by the plants if the phosphorus is unavailable in the soil. This leads to poor absorption of phosphorus, poor root growth, and poor potato tuber formation.

In many soils used for potato growing, in particular compacted and heavily fertilized soil, the healthful activities of soil organisms, may lower the ability of root system to move nutrients. High phosphates concentration without rhizosphere activity leads in having fixed phosphates in soil was unavailable for plants. This causes significant root growth problems in potatoes and thus has a direct impact on yield of potatoes. Once a crop has begun growth mycorrhizal fungi fertilizer can be applied but, unless the right biological phosphorus mobilization processes are used, a large proportion of this investment may go unused. Hence, there is increasing interest of modern farmers to adopt sustainable potato farming technologies which involve boosting soil mycorrhizal fungi for potato cultivation and enhance the overall soil fertility management naturally. In the coming sections, we will discuss how to use mycorrhizal fungi root builder. 

How Phosphorus Nutrient Deficiency Affects Potato Tuber Development

However, phosphorus deficiency causes delay in potato's early stages of growth. This nutrient is essential for the transfer of energy in the plant, for plant root establishment and for healthy tubers initiation. The first apparent signs that the water may be lacking in phosphorus are limited plant growth, floppy stems, possibly purpling of oldest leaves, delayed canopy closure and poor potato tuber formation set. Affected plants may yield reduced production or very small tubers of which the yield may be too small, and consequently not marketable.

Some of the phosphorus deficiency symptoms are that the soil may not contain P for a variety of reasons. The nutrient may be available but it can be “locked up” in soil due to the presence of low soil biological activity and compaction, nutrient balance disruption (acidification or alkalinity), or high soil salt concentrations. This is particularly prevalent in low content of organic matter and microbes in soil. As microbial soil health decreases, natural nutrient cycling decreases and potato plants are not able to take up phosphorus in the most critical growth periods.

Low movement of phosphorus also reduces root growth. Underdeveloped roots are unable to readily tap into the deeper water and nutrients of the soil. This feeds into itself, with weak roots impairing the uptake of nutrient, and then a lack of nutrient uptake slowing the growth of the tuber. The poor potato yields resulting in high percentages of low quality in tubers may not be due to organic fertilizer for potatoes deficiency only, but may instead be caused by underground biological issues, this being the case.

The Hidden Role of Soil Fungi in Potato Production

A healthy soil with potatoes in it is teeming with life helping to make nutrients available to roots and enabling good root growth. Some of the most associated are some of the soil's fungi, particularly those that naturally grow on plant roots, called mycorrhizal fungi and phosphorus (mycorrhizal fungi fertilizer). They form a symbiotic relationship with potato plants through mycelium (microscopic fungal threads) which grow outside the plant root system into the surrounding soil. This substantially enhances the plant's absorption of nutrients and water out of the reach of roots.

It's of critical importance in potato row crops if potassium is limited when soil mycorrhizal fungi phosphorus uptake are involved in root establishment. Phosphorus also is a mobile element in slow soil because during rapid growth periods, the roots may not be able to fully uptake the element. Hence, in the case of beneficial fungi, the answer is in biological phosphorus mobilization. The fungal networks have the ability to take up phosphorus from a very wide area of soil and deliver it directly to plant tissues that have to take it up.

This helps to create active rhizosphere and helps in increased rhizosphere development around developing potato plants. With increase in fungal populations, the soil biology also increases.

Why Weak Root Systems Lead to Poor Tuber Growth

Most of the potato yield problems start with poor and suboptimal root establishment early in the season. The ability to establish good root growth is essential for potato tuber development. Plants can not mycorrhizal fungi phosphorus uptake sufficient amount of mycorrhizal fungi and phosphorus, potassium and micros required for bulking if their root zone is shallow or unhealthy.

Some of the phosphorus deficiency symptoms are low soil root-zone activity is likely caused by the combination of compacted soils, excessive use of synthetic fertilizer, inadequate soil organic matter and inadequate soil microbial diversity. Under these same conditions beneficial fungi and bacteria decrease and soil's natural ability to transport nutrients decrease. Consequently, root colonization is reduced and potato plants are not able to cope with stressful conditions.

If it is taken up to a limited extent, the growth rate of tuber initiation is greatly slowed. A continuing response of the crop may result in continued foliage growth, with in-efficient conversion of energy to quality of developing potatoes. Incompleteness of size, maturity delay and loss of yield quality are common problems experienced by the growers. In certain areas, during the early stages of the growing season, plants may appear healthy and viable, but suffer from poor growth of the tubers later in the season due to an inability of the root system to provide sufficient nutrients to meet a constantly rising need.

Hence, a natural method for the enhancement of potato yield is improving the health of potato roots. While they can also help to anchor the plant in the soil, strong roots provide enhanced nutrition uptake and likely better drought resistance, disease resistance, and nutrient efficiency throughout the growing season.

How Beneficial Soil Fungi Improve Phosphorus Uptake Naturally

Fungi help to transport nutrients naturally within the soil with rhizophagus irregularis spores. After potatoes become infested in the center, fungi grow out from the roots into minute soil pores which the potato roots are unable to reach. They are fungal threads that absorb the nutrients, particularly phosphorus and return it to the plant while receiving plant sugars as consolation prize.

This helps to substantially mobilize nutrient, especially phosphorous, in soils where nutrients are unavailable for biological growth. Over time, nutrients are released to the roots by beneficial fungi; whereas with chemical fertilizers the nutrients may be fixed in the soil. This will help avoid the lock-up of nutrients and contribute to better soil fertility management in the long term.

Biological agriculture can offer some benefits for growers that become apparent at the field level. Better stems, bigger and deeper roots, more uniform tubers. Fungus active areas have better moisture conditions due to the strengthening of soil structure and better soil organic matter activity, etc.

A significant benefit is that useful soil mycorrhizal fungi will persist in providing mycorrhizal fungi phosphorus uptake of nutrients during the season. A living "underwater nutrient system" is developed, rather than all-plant mycorrhizal fungi fertilizer application. This will lead to more sustainable potato production in the long term, at a lower cost and more in balance with the environment.

Building Better Soil Biology for Potato Farming

So it's not just a matter of fertilising more to improve potato production. Today's growers are turning to improving soil biology using mycorrhizal fungi powder and microbial activity to boost soil health and productivity. Good soil health translates to improved nutrient supply, increased abundance of microbial life, and increased nutrient cycling.

The most practical approach to enhance the microbial health of the soil is the application of organic fertilizer for potatoes to this soil using methods such as compost system, cover crops and crop residue incorporation. From the rhizospheres active throughout the season, the important microorganisms are provided food by the best mycorrhizal fertilizer.

Less but balanced soil tillage methods may also help to maintain existing soil fungi naturally. Undisturbed root-zone activity and undamaged fungal hyphae have a positive effect on the increase in soil organic carbon levels. Present potato production systems that enhance sustainability will generally incorporate practices that reduce tillage but also include biological inoculants to ensure maintenance of beneficial microflora.

Balanced irrigation is important, too. Excessively dry soils result in lower microbial activity and waterlogged soils can decrease the amount of oxygen available to the beneficial microorganisms. Please note, correct soil moisture levels provide optimal soil conditions for root colonization, nitrogen and nutrient movement.

Finally, the management of fertility of crops is a big factor in achieving better soil fertility management through mycorrhizal fungi fertilizer. Having diversity in soil microorganisms and less stressed soils by rotating potatoes with legumes and organic cover crops. In time, these practices will make healthier soils to support growth of better tubers without the need of artificial means.

Practical Biological Solutions for Potato Yield Improvement

How to use mycorrhizal fungi root builder? There is a growing trend amongst growers towards the integration of beneficial fungi products into their fertility programs to help them improve their potato yield in the long-term. These solutions ensure more efficient use of nutrients and limit the use of large amounts of phosphorus fertilizers.

Inoculants are plant-side applications of fungi which grow early around developing roots. Early root colonization is crucial as there is a rapid increase in the demand for phosphorus during the early vegetative growth and the stage of tuber initiation. Plants can ‘mingle’ with fungi, and then receive a better supply of nutrients and water during the growing season.

Mycorrhizal fungi powder growing when potatoes are planted are observed to increase crop establishment, enhance uniformity of tubers and promote healthy root systems, according to many farmers. Soil performance continuously gets improved with the passage of year with biological option i.e. improving microbial mass and soil structure naturally which is not possible with chemical option.

With the increase in organic fertilizer for potatoes prices, along with soil degradation, this trend for biological mycorrhizal fungi phosphorus uptake is gaining significance in the world for sustaining potato productivity. Being dependent on active soil biology provides farmers an approach that makes their farming much more stable and resilient for long term production.

Creating Long-Term Success Through Soil Fertility Management

Seasonal fertiliser application is only a small part of the big picture in successful potato production. Long term productivity involves sustaining the soil biology, soil roots and nutrient balance during the growing season. Stressful conditions do not affect a field with good microbial soil health as well as nutrient movement, water holding capacity, and even poor potato tuber formation.

Combined application of soil fertility management practices like balanced fertilization, organic matter incorporation, alleviating soil compaction, crop rotation, and maintenance of beneficial fungi populations will contribute to the improvement of soil fertility management. These strategies can be used together to enhance root-zone activity and eliminate phosphate/nitrogen nutrient fixity, which often hinders nutrient uptake.

However, it is currently a valuable tool for improved P uptake in a natural way which is now being demonstrated by more growers as they are adopting sustainable potato production practices. These biological systems enhance plant nutrient availability via higher rhizosphere activity and better root colonization, thus optimizing plant nutrient uptake, and creating healthier soils for the next growing season.

If a potato grower has difficulty poor potato tuber formation even though he is fertilizing the crop often, he might not be able to help the situation any more by increasing the amount of organic fertilizer for potatoes he applies. Better soil biology and improved root structure; naturally accessing the nutrients already in the field by simply rebuilding soil biology; through the beneficial soil mycorrhizal fungi that is all about the real solution.

Reference: 

• Chifetete, Varaidzo W., and Joanna F. Dames. "Mycorrhizal interventions for sustainable potato production in Africa." Frontiers in Sustainable Food Systems 4 (2020): 593053.
• Pathak, Deepmala, Rafiq Lone, and K. K. Koul. "Arbuscular Mycorrhizal fungi (AMF) and plant growth-promoting Rhizobacteria (PGPR) Association in Potato (Solanum tuberosum L.): A brief Review." Probiotics and plant health (2017): 401-420.