Bradbrook - 2012 - Rice Farming complete with methods to increase ric

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г 1. hydrology 2. climate (rainfall and temperature) 3. soil quality 4. biological constraints (weeds, diseases, and insect pests) 5. socioeconomic factors 1. Hydrology Knowing the water source and how much and how often there is access to this water is the most vital information that will be needed. The topography determines how efficiently water is delivered. The farmer will also need to remember that the water requirements of rice depends on its variety, particularly how long it takes to reach maturity from the time it is planted on the field (either by direct seeding or transplanting). Water needs also depend on the temperature throughout the growing season. High temperatures will naturally mean higher transpiration in rice plants and higher rates of evaporation, which in turn demand higher water usage. Rice plants can withstand a few days of drought, but they thrive best with a constant supply of water. The water requirements of rice extend beyond that of the biological needs of the plant. Water is also needed for land preparation, during which losses from seepage and percolation normally occur, and the need to drain excess water must also be taken into account. The importance of water supply for rice cultivation cannot be stressed enough. Rice is the only cereal crop that is adapted to withstand submerged conditions for lengthy periods. 2. Climate a. Rainfall The amount of rainfall that a given area receives needs to be considered especially if water supply through irrigation is a limited option. The construction of catchment areas or ponds to store rainwater is important whether rainfall is abundant or not. This is because the occurrence of rainfall eannot be controlled, and the sensitivity of the rice plant to drought at specific growth stages can greatly affect the number of grains that it produces. Rice is therefore best suited to areas where the supply of water (artificial or natural) is assured. Lowland rice culture requires an average of 200 mm of monthly rainfall, whereas upland rice culture requires half of that. At the vegetative stage, rice plants need about 125 cm of
ainfall. During the ripening stage, water is not a necessity because rice fields are left to dry up in preparation for harvest. b. Temperature Rice is native to the tropical and sub-tropical zones where day and night temperatures are relatively constant, but in temperate or sub-temperate areas, a period of three to six months of warm weather is necessary to complete one growing cycle. Starting by growing seeds indoors during the colder months could be helpful in areas with short summer months. Rice grows best at a mean temperature of about 22°C throughout the growing period. Rice is sensitive to temperature fluctuations at different stages of its development. For instance, it requires a minimum of 10°C to sprout, the optimum temperature for flowering is around 23°C, and for grain formation it is around 21“C. Temperatures above 22°C accelerate respiration, which in turn reduces the period of grain filling. Rice can tolerate temperatures of up to 40°C. 3. Soil quality Water retention capacity is the most important determining factor for choosing the best soil type for rice. Rice grows best in clay and loamy type soils such as silty clay, silty clay loam, and loamy, especially those containing organic matter. It is also beneficial to assess the soil’s nutrient content to determine if additional enrichments (i.e. fertilization) will be required. Soil pH affects nutrient availability and in the case of rice, a neutral pH is the most favorable for growth. Nitrogen, phosphorus, potassium, iron, manganese and zinc are the six most essential nutrients for rice. Under submerged conditions, the pH level of soil generally falls between 6.5 and 7. At this range, all the essential nutrients are more easily absorbed by the rice plant. 4. Biological limitations a. Weeds Weeds that resemble rice, called “weedy rice”, can easily infest rice fields, particularly those that are direct-seeded. This is because direct-seeded fields are initially not flooded to allow the rice seeds to germinate and attain a certain height. This period of dryness encourages weedy rice to germinate along with the rice 12
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Page 7 and 8: Section 4: Post-harvest Processing
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Page 39 and 40: In both upland and lowland rice cul
Page 41 and 42: Combating disease attack involves h
Page 43 and 44: í The best time to apply fungicide
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2. Requires data-gathering skills:
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1. Sun drying This drying method is
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not commercially viable, b. Single
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irrigation water is obtained from u
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Bradbrook - 2012 - Rice Farming complete with methods to increase ric

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