Crop Data Collection. The IRRI Farm is located in a humid, tropical, lowland environment that allows two and even three rice crops per year. The standard rice-growing seasons in the surrounding area are the dry season (from January to April) and the wet season (from late June to September). Field experiments were conducted at the IRRI Farm during the dry and wet seasons of 1992–2003. The soil at the IRRI Wetland Farm was an Andaqueptic Haplaquoll with pH = 6.0–6.6, organic C = 14.4–16.2 g·kg-1, total N = 1.40–1.50 g·kg-1, and cation exchange capacity = 32.9–40.6 cmol·kg-1.