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Harvest Minerals Limited LSE:HMI London Ordinary Share AU000XINEAB4 ORD NPV (DI)
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Harvest Minerals Limited Outstanding Results of Long Term Testwork

23/04/2020 7:00am

UK Regulatory (RNS & others)

Harvest Minerals (LSE:HMI)
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RNS Number : 5669K

Harvest Minerals Limited

23 April 2020

To view the announcement with the illustrative photos and diagrams please use the following link:

Harvest Minerals Limited / Index: LSE / Epic: HMI / Sector: Mining

23 April 2020

Harvest Minerals Limited ('Harvest' or the 'Company')

Outstanding Results of Long Term Testwork with Coffee

Harvest Minerals Limited, the AIM listed remineraliser producer, is pleased to announce the results of the long term agronomic trials on coffee of KPfértil, its direct application natural remineraliser produced at the Company's 100% owned Arapua Fertiliser Project in Brazil ('Arapua').


-- Testwork conducted by independent consultants Santinato & Santinato Cafés Ltda since 2017

-- Results confirm KPfértil can be used to replace conventional fertilisers as a source of potassium and phosphate

   --    Results in coffee are enhanced when used in association with coffee compost (coffee straw) 

-- KPfértil increases the value of the coffee produced by increasing the proportion of the largest coffee cherries and yield

Brian McMaster, Executive Chairman of Harvest stated, "These results are outstanding and confirm the results of our earlier testwork proving that KPfértil can and should replace the use of conventional fertilisers. As we have progressed with the development and marketing of KPfértil, our understanding of its use and benefits has continued to grow. This is a view echoed by the feedback we are receiving from our customers, our testwork and field demonstrations we are conducting with clients and co-operatives ."



Santinato & Santinato Cafés Ltda ('Santinato'), a renowned agronomic consulting company in Brazil specialising in coffee cultivation, has been conducting trials since 2017 on the suitability of KPfértil as a source of potassium ('K') and phosphate ('P') for coffee plants at one of the Veloso Agropecuária ('Veloso') coffee plantations in Minas Gerais state, Brazil.

The trials consisted of two years of applying a potassium and phosphate fertiliser and a third final year of applying no additional source of potassium and phosphate (fertiliser suppression) to test the effectiveness of different sources of potassium and phosphate. All the soil fertility parameters were measured in May each year, before the peak nutrient extraction by the plants for harvest between May and July in Brazil. All the biometric measurements were made just before the harvest and the productivity, maturation and income measurements were post-harvest.

In total, four experiments were conducted using the following sources of potassium and phosphate:

   --    T1 - Control - No additional sources of K and P applied 
   --    T2 - Conventional sources - Muriate of Potash (KCl) and Simple superphosphate (SSP) applied 
   --    T3 - 100% KP KPfértil - applied to match the K(2) O applied in T2 

-- T4 - KP KPfértil and coffee straw (coffee husks from previous harvests - see figure 1) - applied to match 60% of K(2) O applied in T2 due to application of 5t/ha of coffee straw annually

The application rate of nutrients during each season was as follows:

   --    Year 1 (2017) - 350 kg / ha (N); 80 kg / ha (P(2) O(5) ) and 200 kg / ha (K(2) O) 
   --    Year 2 (2018) - 300 kg / ha (N); 80 kg / ha (P(2) O(5) ) and 350 kg / ha (K(2) O) 
   --    Year 3 (2019) - 300 kg / ha of N 
   --    In the third year, no additional K or P was applied. 

Figure 1: Coffee husks (straw) and applied to coffee plants with KPfértil


Soil pH

The soil pH describes how acid or alkaline the soil is. A pH of 7.0 is neutral and a value below 7.0 is considered acidic. In Brazil, soils are typically acidic, ranging between 4.4 and 5.0.

To achieve production from acidic soils, it is necessary to apply sufficient lime to eliminate the toxicity of Al(3+) and Mn(2+) , as well as supply adequate levels of Ca(2+) and Mg(2+) . This creates conditions that will maximise the uptake of the essential nutrients as well as control soil pathogens.

Figure 2: Change in soil pH over three years in the four experiments

As can be seen in figure 2, the experiments with KPfértil and with KPfértil and Coffee Straw have a much better soil pH. This is because KPfértil contains both Calcium (Ca) and Magnesium (Mg), which neutralise soil acidity whereas the traditional KCl contains salt and chlorides which further acidify the soil. As the pH in both experiments including KPfértil remains above 6.0, it also creates an environment which favours nitrification by soil bacteria, an important step in the nitrogen cycle in soil.

Base Saturation in Soil

Base saturation refers to the percentage of cations in the soil which are occupied by basic cations and not taken by acidic cations (Al(3+) and H(+) ). It gives another indication of the acidity of the soil, what is making up the Cation Exchange Capacity (CEC) and what level of nutrients the soil can retain and release.

Figure 3: Base saturation over three years

As can be seen in figure 5, the experiments with KPfértil and with KPfértil + Coffee Straw have an increasingly higher base saturation over the conventional fertilisers, indicating that the soil is better able to retain and release nutrients.

Calcium in Soil

Calcium has two major effects in soil. Firstly it reduces soil acidity, by binding to cations in the soil and thus preventing acidic cations and secondly it acts to bind organic and inorganic material to develop good soil structure.

Figure 4: Ca in soil

As expected, the results (figure 4) show signifcantly higher residual calcium in the soil from the KPfértil treatments compared to the conventional treatments.

Magnesium in Soil

Magnesium acts similarly to calcium in soil and is an essential nutrient for plant growth, being critical for photosynthesis as a key component for Chlorophyll. The results show that using coffee straw with KPfértil greatly helps with the retention of Mg in the soil over conventional fertiliser or KPfértil in isolation.

Figure 5: Mg in soil

Residual Phosphorous in Soil

Phosphorous is an essential macro-nutrient for plants and is required for metabolic processes including photosynthesis, so it is important to ensure there is sufficient readily available phosphorus in the soil for the plants. As coffee has a heavy requirement for phosphorus, it is important to maintain levels above 40 mg/ dm(3) .

The use of KPfértil resulted in an increase in phosphorous content in the soil over both the medium and long term when applied alone or alongside the coffee straw, indicating that KPfértil continues to act as a slow release source of phosphorous and is able to maintain adequate levels of nutrition compared to conventional sources even after a year of none being applied.

Figure 6: Residual P in soil

Residual Potassium in Soil

Like phosphate, potassium is also a key macro-nutrient in plants . The potassium content in the soil was highest in the first two years using the conventional KCl, however fell substantially in the first year of suppression of the nutrient, as it has low permanence due to being easily leached. Although the level of potassium in the soil was lower for KPfértil, it was able to maintain the correct level for coffee cultivation (3 to 5% of CTC) for longer, notably with the association with coffee straw even during the first year of suppression.

Figure 7: Residual K in soil

Percentage of cherries in the largest size category

Whilst variety, supply and demand have an impact on price of coffee cherries, the largest impact on the value of the cherries independent of market conditions is the size of the cherries. After the Harvest the cherries were analysed by passing them through a series of sieves. The results show that using KPfértil either with or without coffee straw increased the proportion of cherries in the largest size category and therefore the value of the crop.

Figure 8: Percentage of coffee cherries in the largest size classification

Percentage value held in the largest cherries

The percentage value is calculated as the percentage of processed coffee produced after drying and peeling the harvested coffee. Obviously the higher the amount of coffee produced, the higher the value. Figure 9 shows that all three applications produce significantly higher coffee than the control with KPfértil producing the most.

Figure 9: % of value held in largest cherries

Overall, the application of KPfértil either with or without coffee straw produces the most coffee in the largest size classification.


The conclusions made by Santinato in its report were as follows:

1. KPFértil should be used in the planting furrow to replace P(2) O(5) for coffee plants supplied by conventional fertilisers.

2. KPFértil should be used in adult crops to partially replace (<30%) of K(2) O in the first year and an increasing amount in subsequent years.

3. When used in association with coffee straw and / or other organic sources, the results of using KPFértil are enhanced.


For further information, please visit or contact:

 Harvest Minerals Limited   Brian McMaster (Chairman)   Tel: +44 (0) 203 
                             Dr Mark Heyhoe              940 6625 
 Strand Hanson Limited      James Spinney               Tel: +44 (0) 20 7409 
  Nominated & Financial      Ritchie Balmer              3494 
  Adviser                    Jack Botros 
 Shard Capital Partners     Damon Heath                 Tel: +44 (0) 20 7186 
  Broker                                                 9900 
 St Brides Partners Ltd     Charlotte Page              Tel: +44 (0) 20 7236 
  Financial PR               Beth Melluish               1177 


Harvest Minerals Limited (HMI.L) is an AIM-quoted low-cost and high margin Brazilian remineraliser producer, located in the heart of the largest and fastest growing fertiliser market in Brazil.

The company's product, KPFértil, is a registered and approved organic multi-nutrient direct application fertiliser. It contains many of the essential nutrients and minerals required by plants and, unlike most fertilisers, it does not require any complex processing or chemically alteration, instead it can be applied directly to crops.

KPFértil is produced at the wholly owned Arapua project, that consists of a fully permitted mine, production and storage facilities able to produce and deliver KPFértil to customers. Known mineralisation at the Project is expected to support 100+ years' production at 450Ktpa.

Harvest's focus now remains on growing its business and the Company have the dedicated in-country sales and marketing team with the skills, experience and contacts to sell KPFértil into the potential multi-Mtpa market on the doorstep of the project.

This announcement contains inside information for the purposes of Article 7 of EU Regulation 596/2014

This information is provided by RNS, the news service of the London Stock Exchange. RNS is approved by the Financial Conduct Authority to act as a Primary Information Provider in the United Kingdom. Terms and conditions relating to the use and distribution of this information may apply. For further information, please contact or visit



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April 23, 2020 02:00 ET (06:00 GMT)

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