The climate varies from semiarid California, with less than 50 mm rainfall during the growing season, to the humid subtropical Gulf Coast of Louisiana, Texas, and Florida where rainfall may total 700-1000 mm. In all these environments, rice is grown as a single crop per year, but can be ratooned in the warmest, southernmost regions of the Gulf Coast states. All rice in the US is irrigated and direct seeded. In California, pregerminated seed is seeded into standing water by aircraft. Southwestern Louisiana is also wet seeded.
Rice is grown on natural flatlands.
Precision leveling has greatly facilitated water management and is considered second only to the introduction of semidwarf varieties as contributing to increased rice yields. Although US yields are high, production is constrained by several factors. Because all areas are direct seeded, weeds and poor stand establishment are significant problems. In the southern US, many share crop arrangements are short term and tenant farmers are reluctant to spend capital for long-term improvements to productivity. All of US agriculture now operates within a stringent and costly regulatory environment.