The effect of previous cropping and manuring on the yield of potatoes

Abstract

3-year ley).In treatments including 1-year ley, broad red clover was compared with Italian rye-grass, and, in those including 2-and 3-year leys, pure lucerne leys were compared with pure cocksfoot leys and a lucerne/cocksfoot mixture, all the leys being underlst year Superphosphate (19-5% P a O ) (cwt./acre) Muriate of potash (60 % K a O) (cwt./acre) 0 sown in the preceding barley crop. Thus there were nine combinations of cropping sequence and composition of leys and these formed the main treatments of a split-plot design. All leys were compared at two levels of management (M), namely, leys always mown and the produce removed, and leys always grazed by sheep. Defoliation was carried out at the same time, three times each year on all treatments, so that management should cause little difference in botanical composition. Of the allarable plots half were undersown with trefoil in the barley crop immediately preceding the potatoes, and this was ploughed in without cutting or grazing in the autumn; the other half of these plots had no legume ploughed in. Other subtreatments were (a) three levels of nitrogenous manuring (N) applied to all crops as follows:cwt.

Contrasting Effects of Nitrogen and Phosphorus on Potato Tuber Blight

“…In view of the above results it is necessary to make a distinction between the susceptibility of different parts of the potato plant to blight. The delay in the spread of foliage blight brought about by nitrogen applications (Hanley, Ridgman and Jarvis, 1964;Langbein and Pehl, 1962) has been attributed to increased protein N content ofthe leaves (Birnbaum, 1962;Grtimmer, 1955). However, the coincident increase in leaf formation apparently counteracts tfiis effect since attack by Pliytophthora infestans is facilitated by the increased canopy of fohage at higher nitrogen rates (Langbein and Pehl, 1962).…”

Field experiments on the fertilizer requirements of maincrop potatoes

“…Subdivision of the first group of experiments into those following four years grass and those with a two year or longer ley at some point in the preceding four year period did not demonstrate any difference in nitrogen response. Leys may be expected to differ in their residual nitrogen according to their botanical composition, management and fertilizer received (Williams, Clement & Heard, 1960;Hanley et al 1964;Heard, 1965); some account should in practice be taken of these factors, particularly in extreme situations, when estimating how much nitrogen a crop is likely to require.…”

“…Early blight attack might therefore be expected to curtail the nitrogen response. On the other hand, Hanley et al (1964) showed that nitrogen reduced or delayed blight incidence, and this might tend to enhance the nitrogen response when blight occurred. Spring rainfall was included in the multiple regression analysis because it was thought that dry conditions at this time might reduce the nitrogen response, and more particularly retard growth and depress yield at high rates of application.…”

Winter wheat in six-course rotations on light land

“…The design, rotations, subtreatments, soil and method of conduct of the experiment are fully described in previous papers (Hanley & Ridgman, 1979;Hanley, Ridgman & Allen, 1973;Hanley, Ridgman & Jarvis, 1964). During the fourth cycle all treatments and procedures for the first three phases remained the same.…”