noun gris bilong graun, marasin bilong strongim graun, kaikai bilong ol plaua.
Most rural villagers engaged in agriculture in PNG do not use inorganic (manufactured) fertiliser. Small quantities are used by some people growing Irish potato and introduced temperate-climate vegetables, but the total quantity used is negligible. Some villagers use organic materials as green manure fertiliser, particularly in the ‘composting zone’ in the
western part of the central highlands. Minor amounts of chicken manure and other organic fertilisers, particularly household waste, are used,
especially in the highlands. The major oil palm estates compost fruit bunch waste to produce significant quantities of mulch and organic fertiliser for their plantations. For example, Higaturu Oil Palms in Oro Province applied 45 000 tonnes of effluent fruit bunch at a rate of 17.6 t/ha in 2004 while NBPOL applied about 36 000 tonnes.
The oil palm industry uses 83% of the inorganic fertiliser imported into PNG. The coffee, Irish potato, sugar cane and cocoa industries take most of the rest (13% of the total). The balance is retail sales (4%) to villagers, schools, missions, research institutions and other bodies, most of which is used on introduced vegetables. About 70% of retail sales of inorganic fertiliser were made in Mount Hagen and are used for temperate vegetable and Irish potato production in Western Highlands and Enga provinces.
The most important inorganic fertilisers used in PNG are ammonium chloride and urea. Other fertilisers include potassium chloride, ammonium nitrate, mono ammonium phosphate, mixed fertiliser (the most common being nitrogen–phosphate–potassium (NPK) mixes) and other types, including micronutrients, dolomite, kieserite and sulfur. Many fertiliser mixes now contain 0.3% boron. This follows research in the highlands in the late 1970s and 1980s which showed that application of very small amounts of boron fertiliser increased the yield of many crops
in the highlands, including introduced vegetables.