Crop study update

13 June 2013

Sirius Minerals Plc

Crop study update

§ Studies validating polyhalite to be an effective, valuable fertilizer that outperforms traditional potassium chloride ("MOP") on both yield and quality

§ Positive seed germination and early growth results demonstrate significant potential for polyhalite as an excellent 'starter' fertilizer

§ On-going studies continue on major crops at leading agricultural universities in Brazil, China, USA, UK and soon to commence in India and Malaysia

The Directors of Sirius Minerals Plc (AIM: SXX, OTCQX: SRUXY) ("Sirius" or the "Company") are pleased to provide an update on the latest results from its on-going global crop study programme. 

The programme has been developed to provide unbiased global agronomic research in cooperation with leading universities. Studies have included major crops of global importance such as corn, wheat, cotton, oil seeds and fruit and vegetables such as potatoes, onions and peppers. The studies are being undertaken in key markets to enhance the understanding of performance of polyhalite fertilizers in local growing conditions. These include the UK, the United States and China and have recently been expanded to include Brazil and are soon to commence in India and Malaysia.

The Company has conducted a webcast detailing the results of the programme which is available from the Company website or http://www.media-server.com/m/p/mbtwb3vp.

Current highlights of the programme include:

·; Results at Texas A&M on both yield and quality of onions, show a 21% colossal onion yield increase over MOP and higher quality when measured as pungency;

·; Early growth data from Durham University shows increase in cotton aerial fresh weight of up to 134% over MOP and wheat aerial fresh weight of up to 95% higher than MOP;

·; Early growth data from trials at Shandong Agricultural University in China on corn showed a 25% increase in stem diameter, 11% increase in corn height and up to 21% increase in corn shoot biomass by using polyhalite over traditional MOP. Early growth data from trials comparing polyhalite based NPK blends and MOP based NPK blends showed up to 44% increase in corn shoot biomass from polyhalite based blends;

·; Corn seed germination results at University of Florida show significant increase in seed germination using polyhalite as a potassium source or polyhalite based NPK blends.

Chris Fraser, Managing Director and CEO of Sirius, commented:

"These results are further validation of the market-changing potential of polyhalite as a unique multi-nutrient fertilizer. The wide ranging crop trial programme has been designed to deliver relevant and valuable information for the customers we are in on-going discussions with."

For further information, please contact:

About Sirius Minerals Plc

Sirius Minerals is a globally diversified potash development company. Its primary focus is to bring on stream major potash mining facilities through the acquisition and development of projects overlying recognised potash deposits. Today it holds properties in the United Kingdom (North Yorkshire), the United States (North Dakota), and Australia (Queensland). Incorporated in 2003, Sirius Minerals' shares are traded on the London Stock Exchange's AIM market. Its shares are also traded in the United States on the OTCQX through a sponsored ADR facility. Further information on the Company can be found at www.siriusminerals.com.