第二章 作物需水量和灌溉用水量

仅供学习使用 请勿转载

第二章 作物需水量和灌溉用水量(Crop Water Requirement and Irrigation Water Use)

第一节 作物需水量 第二节 灌溉制度 第三节 灌溉用水量 第四节 灌水率

仅供学习使用 请勿转载

第一节 作物需水量一、基本概念

二、研究作物需水量的意义三、作物需水量的推求方法

仅供学习使用 请勿转载

一、基本概念

1、作物需水量 2、田间耗水量

仅供学习使用 请勿转载

1、作物需水量(Crop water requirement)植株蒸腾 Traspiration

作物需水量 = 植株蒸腾 + 株间蒸发=腾发量 Evapotranspiration(ET)The evapotranspiration of a crop is the total amount of soil water used for transpiration by the plants and evaporation from the surrounding soil surface. 株间蒸发 Evaporation The evapotranspiration is commonly expressed in millimetres of water used per day (mm/day)

仅供学习使用 请勿转载

蒸腾(Transpiration)

作物根系从土壤中吸入 体内，通过叶片的气孔 扩散到大气中去的水分 refers to the movement of water from the soil into a plant, up the plant body, and out the plant’s leaves into the atmosphere.

仅供学习使用 请勿转载

蒸腾(Transpiration)

仅供学习使用 请勿转载

蒸腾(Transpiration)

Transpiration takes place so quickly, that in a rainforest, water that is in the soil in the morning travels into, up, and out of a tree in time to become rain in the afternoon.

(This has prompted biologists to say that “rainforests make their own rain.”)

仅供学习使用 请勿转载

蒸发(Evaporation) 植株间土壤或田面 蒸发的水分 refers to the movement of water from the soil surface or water surface in paddy field into the atmosphere

evaporation from the soil surface is at most equal but usually considerably less than evaporation from an open water surface

仅供学习使用 请勿转载

2、田间耗水量( Consumptive Use of Water) 旱地耗水量 = 作物需水量 稻田耗水量 = 作物需水量 + 田间渗漏

水稻田的渗漏 Percolation in paddy fieldPercolation

仅供学习使用 请勿转载

影响作物需水量的因素Factors Affecting Crop Water RequirementFactor Climate Effect on crop evapotranspiration high low hot cool dry wet windy no wind no clouds cloudy mid/late initial or season ripening dense wide plant plant spacing spacing moist dry

Crop

Soil moisture

仅供学习使用 请勿转载

气象因素(Climatic factors)

Radiation: supplies energy to evaporate water from liquid to vapor Air temperature: determines how much water air can hold Humidity: how much water is in the air Wind: how easily a molecule moves into the atmosphere

仅供学习使用 请勿转载

二、研究作物需水量的意义

Design new irrigation systems

schedule (operate) existing ones

仅供学习使用 请勿转载

三、作物需水量的确定Determining Evapotranspiration – Direct measurement (Lysimeters) – Calculated (equations)

仅供学习使用 请勿转载

1、作物需水量的观测Measurement of Evapotranspiration

Lysimeter

仅供学习使用 请勿转载

Measuring Crop ETInside view of weighing lysimeter

1995 Soybean Crop

3m

仅供学习使用 请勿转载

2、作物需水量的计算Calculation of ET 直接计算需水量 通过计算参照作物需水量来计算实际 作物需水量