Several forces have converged to create an exceptionally positive environment for global agriculture — one that we believe will support powerful growth in the years ahead.
Ongoing increases in world food demand have proven to be a constant driver for agriculture and we believe this will continue, as the needs of an ever-expanding population and improving economies in developing countries have transcended short-term economic shifts.
This means that crop productivity must continue to improve and that maintaining historical trends in yield growth is not enough to keep pace. As an example, the United States — the world's largest agricultural exporter — produced the largest corn and soybean crops in its history during the past four years, yet stocks have continued to decline because of escalating demand.
More importantly, global grain supplies have been drawn down to levels that cannot handle short-term supply shocks. Overcoming this challenge will require a sustained commitment to increase food production, including improved fertility practices.
Rising crop prices are a reflection of the global priority now placed on agriculture. Today, farmers in nearly every country, growing almost every crop, have an important economic incentive to increase production. As they make decisions on planting and crop inputs, they recognize that the opportunities are unprecedented and that improving fertilizer applications can help optimize production and maintain the strength of their soils for future years.
While we see potential across all three primary nutrients, we believe potash represents the greatest opportunity — especially for PotashCorp. More than eight years ago, we began planning and investing to raise operational capability, knowing it takes many years to build the facilities and infrastructure necessary to increase production. Now, as we enter an environment in which global potash demand is expected to pressure existing operational capabilities, we believe we are uniquely positioned to introduce our new production as the world needs it. While some saw our decision to launch these projects before demand arrived as a risk, we were unwavering in our conviction that the long-term trends driving demand would continue and that these investments would deliver exceptional value in coming years. We also invested in PotashCorp's future growth through the swift execution of a $2 billion share repurchase program in the fourth quarter. This marked the third time in six years that we have bought back shares in our company. We invested $6.2 billion over this period to purchase more than 65.4 million shares at an average price of $95 per share. This strategic use of capital has created value for our long-term investors by providing them with a greater opportunity to benefit as demand for our products grows.
Our confidence in the future is buoyed by the transition that took hold in 2010, when global potash shipments reached an estimated 52.0 million tonnes. We believe this is only the beginning of the rebound and that shipments in 2011 could reach 55.0-60.0 million tonnes, depending on how aggressively farmers and fertilizer dealers move to replenish depleted inventories in the soil and supply chain.
North American demand is expected to remain strong — our first-quarter volumes are already fully committed - as farmers are moving quickly to capitalize on favorable crop economics. We anticipate demand in this market will be near historical highs, and reach approximately 10.0 million tonnes in 2011.
Farmers in Latin America are responding to strong grower economics, leading to robust demand for all fertilizer products. We believe fertilizer shipments to this market will reach record levels with potash demand of approximately 10.0 million tonnes, including Brazilian imports of 7.0 million tonnes.
India, coming off a year of record potash demand, is expected to move quickly to secure new supply contracts and ensure product is available to meet its growing needs. Given the country's rising food requirements and government support programs, we believe its potash demand this year could reach record levels of approximately 6.5 million tonnes. Other Asian countries (not including China and India) are expected to import around 6.5 million tonnes in 2011.
China's consumption of food and potash is driven by the powerful multiplier of hundreds of millions of people gaining access to higher incomes and the ability to purchase more nutritious food. Although its demand recovery was slower than most markets in 2010, we believe China is committed to improving the fertility of its soils and increasing crop yields. Early in first-quarter 2011, it signed a six-month contract at higher prices with Canpotex for shipment of 600,000 tonnes — a contract that allows Canpotex to remain agile in a tightening potash environment. We believe China could make larger volume commitments in the latter half of the year, and anticipate that its consumption could approach 11.0 million tonnes in 2011, including imports of 7.0-7.5 million tonnes.
With our current estimate of global potash operational capability at 61 million tonnes, we expect supply to remain under pressure throughout 2011. Given the tightening fundamentals, prices to all markets have begun to move higher. This has taken effect more quickly in the U.S., as market-focused farmers and fertilizer buyers secured the potash needed to capitalize on strong agricultural returns. We see the potential for similar trends in offshore spot and contract markets as the year progresses.
In this environment, we estimate our 2011 potash gross margin between $2.5 billion and $2.8 billion and record potash shipments within the range of 9.5-10.0 million tonnes.
In phosphate, we believe strong demand coupled with historically low inventories will result in relatively strong market conditions for both solid and liquid fertilizers through the first half of 2011. Phosphate feed prices are expected to move higher early in the year, reflecting an announced average $50 per ton price increase for the first quarter. Higher realizations on phosphoric acid industrial contracts, which are time-lagged to input costs, are expected to improve industrial margins as the year progresses. In nitrogen, the expectation of increased U.S. corn plantings and rising industrial demand is likely to result in strong prices through at least the spring season. We forecast phosphate and nitrogen will combine to generate 2011 gross margin in the range of $1.0-$1.2 billion.
We expect capital expenditures for 2011 to approximate $2.0 billion, with $1.4 billion relating to our ongoing potash expansion projects.
Our 2011 annual effective tax rate is forecast to be 25-27 percent and provincial mining and other taxes are expected to approximate 4-6 percent of total potash gross margin. Other income is forecast to exceed 2010 levels and be between $300 million and $350 million, while total selling and administrative expenses are estimated to be in line with 2010 levels. We expect interest expense to approximate $120-$130 million.
PotashCorp expects first-quarter net income to be in the range of $2.10-$2.70 per share (pre-split), with forecast full-year earnings in the range of $8.40-$9.60 per share (pre-split). After giving effect to the previously announced three-for-one stock split that will be effective in February 2011, these totals will approximate $0.70-$0.90 per share (first quarter) and $2.80-$3.20 per share (full year), respectively.