Getting the Most from Plant Water Use
Looking back on the 2000 crop year, we broke all kinds of records and learned all kinds of new lessons. With all that information, now is a good time to reflect and take stock of where to go in the coming year. An article I read not too long ago in the Better Crops with Plant Foods journal reinforced the importance of considering as many of the contributing factors as possible when managing crop production. One such factor is the relationship between phosphorus and crop water use efficiency. This article, which appeared in Better Crops with Plant Foods Vol. 83 (1999, No. 1), pg 24-27, offered the following tips.
Phosphorus helps crops use water more efficiently. Water use efficiency (WUE), how much water a crop uses per unit of yield produced, can be expressed as units of yield per inch of water used. Phosphorus increases WUE and drought tolerance of crops in several ways.
- Earlier and fuller canopy development reduces soil water evaporation and the erosive energy of raindrops.
- Heavier crop residues decrease soil crusting and increase soil organic matter and tilth, resulting in increased water infiltration and reduced runoff and soil erosion.
- Root activity and proliferation are increased, thereby expanding the soil volume from which roots extract water and nutrients.
- Vigorous and healthy plants have greater resistance to diseases and nematodes and can better compete with weeds.
- Earlier maturity avoids heat and moisture stress during the pollination period for corn and other crops.
- P fertilization increases root density and rooting depth, thus increasing the amount of water available to the plant. Furthermore, when P increases yield, WUE also increases
- Phosphorus placed in a concentrated band near the seed can encourage vigorous early growth that results in a larger root system, increased WUE, and resulting in higher yields. Starter P can help overcome slow growth due to cold soil temperatures.
