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KALRO has mapped several regions in Kenya affected by soil acidity. Three major soil classes in Kenya majorly affected by acidity include Nitisols, Acrisols and ferralsols. Regions such as Kisii, South Nyanza, Siaya, Busia, Bungoma, Kakamega, Kericho,Narok,  Uasin Gishu, Marakwet, Baringo, Murang’a, Nyeri, Embu and Meru have Ph less than 5.5. These regions form the food basket of the country.  On average, crops require Ph range of 6.0 – 7.0 for optimal growth. However, different crops have various degrees of tolerance to acidity. Chillies, sweet potatoes and irish potatoes are tolerant to acidity and can do well in soils with pH values below 6. Most of the horticultural crops (onions, spinach, carrots and cabbages) do not tolerate acidity and can only grow well in soils with pH values of 6.2 – 7.4. Other crops like maize lie in the medium tolerance range and would do well in 6.0 pH values.

The blue coloration show acidic regions in Kenya.

According to Timothy Munywoki, Amiran Cereal Expert, soils become acidic when basic elements such as calcium, magnesium, sodium and potassium held by soil colloids are replaced by hydrogen ions. Soils formed under conditions of high annual rainfall are more acidic than are soils formed under more arid conditions. The major reasons for soils to become acidic include: Rainfall and leaching, use of ammonium-based fertilizers, acidic parent material and organic matter decay. The major cause of soil acidity in most agricultural soils is majorly attributed by use of Nitrogen fertilizers in ammonium form. Munywoki further clarifies that ammonium fertilizers react in the soil by the process of nitrification to form nitrate(NO-) and in the process H+ ions are released which are responsible for soil acidity.

It is worth noting that the availability of some plant nutrients is greatly affected by soil pH. The ideal soil pH is close to neutral and falls within a range from a slightly acidic pH of 6.5 to slightly alkaline pH of 7.5. Acidity damages plant root hairs thus affecting the absorption of nutrients. Phosphorus is locked in acidic conditions and at alkaline pH values, greater than pH 7.5 for example, the HPO4 2- phosphate ions tend to react quickly with calcium (Ca) and magnesium (Mg) to form less soluble compounds. At acidic pH values, the H2PO4- phosphate ions react with aluminum (Al) and iron (Fe) to form insoluble compounds. Most of the other nutrients (micronutrients especially) tend to be less available when soil pH is above 7.5, and in fact are optimally available at a slightly acidic pH, e.g. 6.5 to 6.8. The exception is molybdenum (Mo), which appears to be less available under acidic pH and more available at moderately alkaline pH values.

Farmers use different liming materials to increase the soil Ph. In modern times especially Wheat and Maize farmers in Narok and Uasin Gishu lease farms for say two seasons which makes them shy away from using lime due to the fact that the normal liming material would take 2 -3 years to correct the soil Ph. Munywoki states that it is through these uncertainities that made Amiran to look for solution.

Calciprill( 90.3%CaC03 + 3.3% MgC03) from  Omya International  distributed by Amiran Kenya  has reaction time of 4 – 6 weeks.   Calciprill has Chemical, physical and biological effects when applied in soil as shown below:-

Low pH affects the fertilizer efficiency as shown

Physical effects of liming

  • Manage soil acidity
  • Improve the structure of the soil
  • Increase the soil’s ability to store water
  • Promote root development

When and why do I need it?

  • Soil with low Calcium status leading to Plant Nutrient Deficiencies –  Agronomic
  • Soils with Low pH – Soil Chemistry
  • Soils Improper Cation Ratios – Soil Chemistry
  • Soil Compaction / Hardpan Compaction due to inappropriate Ca : Mg – Soil Physical
  • Ease of Usage / Transport / Application – The Practical /Economical Considirations

Key attributes of Calciprill

  • Calciprill has a very high ECCE( effective calcium carbonate equivalent)giving a guaranteed quick reaction time. This brings about a quicker correction of acidic soil pH’s sooner than any other liming product.
  • Calciprill can be blended into your fertiliser mix for the convenience of a single pass application.
  • Calciprill can be applied directly to the soil or to your growing crop without causing phytotoxicity effects.
  • Calciprill is applied at lower rates compared to conventional agricultural limes.
  • Calciprill provides calcium nutrient to your growing crop.
  • Reaction time 4-6 weeks after application.
  • Average use rate through bunding 50Kgs/Acre realizing 0.3 to 0.5 pH increase in the root zone.
  • Crop focus ; Maize, wheat, barley, legumes, potatoes, coffee, Brassicas and avocado.
  • Average 13% yield increase especially on maize, wheat, barley, legumes and potatoes
  • Depth of pH adjustment: 30cm to 90cm.
  • Sustainability. Changes evident up to 13th month.
  • Significant changes in nutrient availability and uptake. P and Ca