Soils can become acidic through the application of fertilisers, nutrient uptake by crops or soil chemistry. Acidic soils can reduce the availability of nutrients or impede root development to negatively impact crop growth, alongside promoting the development of certain diseases such as club root in Brassica. Conventional control of pH is achieved through the application of limestone which can be expensive to implement and difficult to achieve in small-scale field settings. Conventional liming is also slow acting and long lasting, meaning that it can be difficult to achieve optimum pH levels for different crops grown in rotation.
pH Shift is an emulsion of micronized lime achieved through the use of patented surfactant technology which can be applied directly to the soil as a liquid. This facilitates fast-acting, precise control of soil pH to help growers achieve optimum conditions for their crops. This is of particular relevance as growers increasingly adopt GPS-mapping technology to aid them in precision control of fertiliser/soil pH control. pH Shift will also be of interest as a soil drench when planting brassica transplants grown in compost to provide early-season pH control before the crop establishes to aid club root control.
While the benefits of pH adjustment in field production of vegetables are well established, the majority of growers currently rely on conventional bulk application of granulated limestone to achieve pH adjustment, although these can vary based on lime source and offer additional minerals to the soil such as magnesium (e.g. dolomitic limestone). Rough, imprecise control of pH achieved through conventional liming can be insufficient, limiting optimum nutrient availability and uptake in the crop and thereby limiting potential yield from the farming land.
pH Shift offers a new way for growers to have rapid, targeted, control of soil pH to ensure that field conditions are optimised for crop production. 3 Managing Soil pH Soil pH can be subject to a wide range influences, and can in turn influence the quality and yield of a crop through a variety of routes. Agricultural soils in Africa typically have a pH of between 4 to 7, although levels below a pH of 4 can be seen in certain parts of the continent. Intensive cultivation and the use of acid forming fertilizers are the major contributing factors enhancing the spread of soil acidity in the country. History has proven that when soil pH is rectified there is a significant uptake of Calcium, this is the "bus" that takes all the other nutrients around the plant that are essential for plant growth. While soil pH can be balanced before planting, acidification may take place due to the application of acidic fertilisers (e.g. sulphur, urea or ammonium), breakdown of organic matter or nutrient uptake by the crops. Smaller farmers often face the logistical challenge of trying to get 2,5 to 3 tons per hectare of lime into their soil. Where the farmers are women this can prove to be even more cumbersome and difficult.
Soil pH can have a significant impact on the availability of nutrients for the growing crop. Lower pH soils promote the dissolution of Al3+ ions which will negatively impact plant growth through inhibition of root growth, impacting soil penetration and root architecture. Aluminium toxicity will reduce a plant’s ability to absorb sufficient nutrients from the soil, risking deficiencies of nitrogen, potassium, phosphorus and manganese. Other essential micro nutrients (molybdenum, iron and copper) are less soluble in acidic soils, reducing their availability to the crop. As a result of these influences, crops grown outside of their preferred pH range are at increased risk of developing deficiency symptoms or being prone to stress which can ultimate impact yield outputs. This can also decrease the efficiency of nutrient applications, requiring growers to utilise more expensive methods of applying the nutrients to their crops (e.g. foliar applications) to achieve desired yield outputs.
pH Shift represents a step change in lime application – the use of a the patented surfactant means that micronized lime can be held in a stable, permanent suspension as an emulsion with the particles prevented from forming aggregates and dropping out of solution, ensuring a much more evenly dispersed solution. This means that micronized lime can be applied to the soil to achieve the greatest level of reactivity compared with conventional lime products. As a liquid it can be applied through precision spraying for near-immediate effect, even when compared with micronized lime prills that will still require slow dissolution once spread into the soil.
The liquid nature of pH Shift immediately sets it apart from other micronized lime products which are granular based.
It’s uniquely suitable for application in areas of land that are difficult to access with standard equipment, and can be applied as or when required (independently of weather conditions) and using existing equipment without requiring external contractors. The liquid nature of pH Shift may also allow greater penetration into the soil, allowing pH adjustment to be carried out throughout the entire root zone (unlike granular micronized products which only impact the top few cm of the soil). The fast acting, short-term action will also be relevant to growers using multi-crop rotations.
Lastly, as growers continue to adopt precision nutrient application approaches based on GPS/ mapping technology, the liquid nature of pH Shift will directly contribute to spot treatments and precision controlled application of lime. This may come at a greater cost than conventional lime, but is likely to be far more rapidly acting than a base dressing of plugs, achieving effective control from the point of planting. Conventional soil pH assessments are based on composite samples that give an average pH across a field, but there is increasing shift towards the production of a contoured pH “heat map” based on regular sampling across the field using a GPS-based grid system. If this information is combined with precision application of pH Shift it will be possible to greatly promote a uniformity of pH across a field, improving crop uniformity and improving overall quality.
In cases of pH-linked disease development this will also help to preclude disease-rich areas of the field that could provide a site of infection for the wider crop. Standardising pH across the field will also allow growers to achieve greater uniformity of nutrient uptake and use.