Optimum Leaf Levels of Nitrogen, Phosphorus and Potassium in Sweet Corn and Snap Beans

Abstract

Optimum nutrient levels were derived by comparing the polynomial tegression curves relating leaf analyses and crop yields with rates of applied nitrogen, phosphorus and potassium. IJppermost mature leaves were used for analysis, and samples ivere collected-it specific physiological stages of development.In two seasons the optimum ler,-els in sweet corn difiered by 7,25 a.nd 9 per ccnt, and in snap beans by 12. 29 end 1l per cent for nitrogen. phosphorus and potassium resp.ectivel)'. A lorv moisture supply was generally associated with lorver optimun: levels for all three nutrients, but "excess" moisture had only slight effects on these levels for any nutrient.Optimum nutrient levels rvhich rvere calculated from ample moisture conditions s'ere, for the tassel-emerging stage of srveet corn, 3.5, 0.18 and 2.5 per cent, and at the early flou'er siage bf snap beans 5.1, 0.'10 and 2'0 per cent fo.r'n-itrogen, pl-rosphorus and poiassium,.respectively. At the sixth to seventh leaf stage of su'eet corn optimum levels were higher tor nrtrogen and potassium'but lorver for phosphorus (3.8, 3.1 and 0.34 per cent lgsPe,ctively), and at thc pollen-shedding stage the levels rvere only slightly different than at tassel-emergence.

Influence of root temperature on the potassium requirements of young tomato plants

“…Critical concentrations for P in wheat were increased by low root temperature (Sheppard et al, 1986) and increases in requirement for K have been found with soil moisture deficits and limiting supplies of Mg and Na (Mackay and Leefe, 1962;Smith et al, 1982). In the present paper we examine the influence of low root temperature on the K requirements of young tomato plants grown with adequate and limiting supplies of the element.…”

The Influence of Irrigation Treatments on Yields and on Fertilizer Utilization by Sweet Corn and Snap Beans

“…The direct effects of fertilizer application rates on yields and nutrient uptake are described in another paper (11). Only the interaction effects of irriEation and fertilizer treatments on vields and nutrient content of the crJps will be considered here.…”

Biochar affects growth and shoot nitrogen in four crops for two soils

“…However, the decreases in shoot nutrient concentrations with many biochar treatments may be predictive of eventual growth reductions because the concentrations generally were below nutrient sufficiency concentration ranges for these crops even without the addition of biochar ( Table 5 ) ( Hanlon & Hochmuth, 2000 ; Hartz, Johnstone, Williams, & Smith, 2007 ; MacKay & Leefe, 1962 ; Mueller, 2019 ). Decreases in shoot N were more significant for the manure-based biochars (SS and PL) and blends (55 and 82) than for the cellulosic biochars.…”

“…Enhanced growth with biochar treatments containing animal manure (55, 82, SS, and PL) was likely due to a Nenhancing (Clough et al, 2013) and a general nutrientenhancing effect (Agegnehu et al, 2017) because the initial soil levels of N, P, and K appeared to be low (Table 1) and the levels of these elements high in the at least partially manure-based biochars (Table 2). However, the decreases in shoot nutrient concentrations with many biochar treatments may be predictive of eventual growth reductions because the concentrations generally were below nutrient sufficiency concentration ranges for these crops even without the addition of biochar (Table 5) (Hanlon & Hochmuth, 2000;Hartz, Johnstone, Williams, & Smith, 2007;MacKay & Leefe, 1962;Mueller, 2019). Decreases in shoot N were more significant for the manure-based biochars (SS and PL) and blends (55 and 82) than for the cellulosic biochars.…”