Sirius Minerals Regulatory News (SXX)

24 September 2014

Sirius Minerals Plc

Cabbage Crop Study Results

§ POLY4 improved cabbage yield and growth whilst maintaining quality

§ POLY4 outperforms SOP in yield by 7% and MOP by 105% in a 'straights' trial

§ POLY4 based NPK blend delivers a significant 90% yield increase over traditional MOP based blend

§ Webcast available on company website

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 ongoing global crop study programme.

This update provides details of a crop trial on cabbages carried out in partnership with the University of Florida. Significantly, the results demonstrate the suitability and effectiveness of POLY4 on cabbage, which requires precise and balanced fertilization.

Geographically the major cabbage producers are China, United States, India, Russia, Japan and the Republic of Korea. China dominates the production (47%) and the total market equates to ~70 million tonnes being worth ~US$17 billion annually.

This recent trial proves that POLY4 significantly outperforms MOP, the traditional source of potash and demonstrates an improvement over the premium potassium fertilizer, SOP. In addition to the yield benefits of using POLY4 in cabbage farming, further highlights from the trial are outlined below:

§ A 77% increase in tissue potassium is indicative of improved nutrient use efficiency (NUE) with blends

§ Further validation of POLY4's unique ability to influence tissue magnesium levels showed a 69% increase in tissue magnesium content in the straight trial and an 82% increase in the blend part of the study

§ An increase in root mass is indicative of POLY4 supporting plant growth and development which culminates in increased yields

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

"Besides the broad-acre crops it has been encouraging to see the positive results of POLY4 on a more fertilizer-sensitive crop such as cabbages which are known for their precise demands from the nutrient source. POLY4, which has a range of nutrients, coupled with appropriate nutrient release rates, is an effective and quality fertilizer."

An agronomy update presentation and webcast has been uploaded to the Company website www.siriusminerals.com.

For further information, please contact:

About Sirius Minerals Plc

Sirius Minerals is a potash development company with properties in the United Kingdom (North Yorkshire) and the United States (North Dakota). Its primary focus is the development of the York Potash Project which has the world's largest and highest grade deposit of polyhalite, a multi-nutrient form of potash containing potassium, sulphur, magnesium and calcium. 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.