Rothamsted irrigation 1964–76

Abstract

A series of irrigation experiments was done at Rothamsted where the soil is a flinty silty clay loam over flinty clay. The results are compared with those obtained by Penman (1962, 1970, 1971) at Woburn where the soil is a loamy sand over sand. The limiting deficits, JD ( , above which irrigation increased yields, were about 2-6 times greater at Rothamsted than at Woburn; this ratio approximates to the ratio of the water-holding capacities of the soils (-0-1 to -15 bar) to a depth of 1 m. The limiting deficits at Rothamsted were 80 mm for spring-sown field beans, 84 mm for main-crop potatoes, 100 mm for spring barley and 140 mm for spring and winter wheat. The responses to irrigation were not determined accurately as there were few years with a large response for any crop. However, the evidence is that the maximum response that could be expected for potatoes was 0-19 t/ha/mm water, and for grain dry matter of beans 0-006 t/ha/mm. The figure for potatoes agrees with that obtained by Penman at Woburn; the response of beans was much smaller at Rothamsted, partly because of severe attacks of broad bean stain virus.

Soil water extraction patterns of lucerne grown on stony soils

“…Total rainfall (1 July 2011 to 30 June 2012) experienced by the lucerne crops was 580 mm at the stone free site and 645 mm at both stony sites which was accumulated in 52 rain days (>1 mm). Total Penman potential evaporation (P ET ) (French and Legg 1979) was 910 mm, and exceeded rainfall from about September to May. Long term mean annual rainfall for Lincoln is 630 mm and annual mean P ET is 1095 mm.…”

“…The soil diffusion constant was 4.4 mm day -1/2 . Potential E s is set by P ET , and reduced proportional to ground cover (French and Legg 1979) which was calculated daily from interpolated LAI measurements. It was assumed E s only occurred in the top 0.2 m of soil, and to avoid overestimation, the Ritchie calculation was modified to account for additional soil drying by crop roots ).…”

“…Potential transpiration demand is commonly calculated using the Penman-Monteith equation from weather variables (Monteith 1965) and adjusted to account for the effect of the crop canopy (French and Legg 1979). The canopy intercepts incoming solar radiation which supplies the radiative energy to drive evaporation, which is also controlled by the vapour pressure deficit (VPD) between the evaporating surface and atmosphere (Penman 1948).…”

IMPACT OF MOISTURE STRESS AND NITROGEN ON CROP GROWTH RATE, NITROGEN USE EFFICIENCY, AND HARVEST INDEX OF COTTON (Gossypium hirsutum L.)

“…Soil water content in root zone was measured by using the gravimetric procedure of direct soil water measurement. The moisture content in root zone was computed by using the method as described by (Penman, 1970;French and Legg, 1979). Soil sampling from experimental plots (0-60 cm depth) was done on regular basis on alternate days with the help of soil sampling probe throughout cropping period (May-December) for determination of soil moisture.…”

Improving irrigation practice in New Zealand

“…This is time consuming and expensive to measure directly. However, we have found that, the model of Penman [5], as refined by French and Legg [6], works well for annual arable crops. This model quantifies the yield response to drought by using the maximum potential soil moisture deficit (MPSMD) experienced during the growth of the crop as the measure of stress.…”