Soil Nitrogen Application Research Articles

Fiber, Nitrate, and Protein Content of Amaranthus Accessions as Affected by Soil Nitrogen Application and Harvest Date

Abstract Six accessions of edible amaranths (Amaranthus spp. L.) of varied geographic and genotypic origin were grown in a soil enriched with 0, 50, or 100 kg·ha–1N. Leaves were harvested at 25, 35, 45, 55, and 65 days after germination (DAG) and analyzed for crude protein (CP), neutral detergent fiber (NDF), and NO3– N. In grain-bearing accessions, leaf CP content increased with N application but declined linearly over harvest dates. In vegetable types, leaf CP levels tended to fluctuate over time. In both types, NDF content declined with N application, whereas response to harvest date varied. Leaf NO3– increased two-fold in plants from fertilized plots compared to plants from unfertilized plots, but declined rapidly with time. Leaf content of NO3– did not exceed 239 mmol·kg–1 dry weight with any N fertilization treatment. Edible amaranth appeared to be adapted to soils and climate of the southeastern United States. A. tricolor was most susceptible to disease among the accessions evaluated.

Maize response to intermittent submergence, straw mulching and supplemental N-fertilization in subtropical region

A 2-year field study was undertaken on a sandy loam in a tropical monsoon region to determine the growth and yield response of maize (Zea mays L.) to 10–11 day intermittent submergence at two growth stagesviz., 20 (stage 1) and 40 (stage 2) days after planting, in combination with two rates of rice straw mulch (0 and 6 t/ha) and three levels (0, 30 and 60 kg/ha) of soil-applied supplemental nitrogen.

Effect of Multiple Factor Source-Sink Manipulation on Nitrogen and Carbon Assimilation by Soybean

The objectives of this study were to determine the effect of light enhancement and hastened reproductive development on nitrogen and dry matter accumulation by field-grown soybean (Glycine max [L.] Merr.). The impacts of photosynthate supply and reproductive development on change in the season-long profiles of in vivo leaf nitrate reductase (NR) activity and root nodule acetylene reduction (AR) activity were evaluated.Light enhancement resulted in significant increases in dry matter accumulation, root nodule fresh weight and AR activity. Seed yield was increased in both light enhanced treatments in 1978 and in one in 1979.Hastened flowering and seed development was accomplished through photoperiod manipulation within a single genotype. Seasonal decline in leaf NR activity was most rapid in plants entering reproductive development early. An early increase in root nodule fresh weight and AR activity was also observed in response to this treatment and was followed similarly by early decline.The addition of high levels of soil-applied nitrogen increased leaf NR activity and delayed late season decline in NR activity for both control and early reproductive plants. Nitrate supply was therefore implicated as limiting to leaf NR activity during the decline associated with flowering and early seed development. A limited additional increase in leaf NR activity was observed in response to light enhancement plus soil-applied nitrogen. As no significant increase in leaf NR activity was observed in response to light enhancement alone, leaf nitrate supply was further implicated as more limiting to leaf NR activity than was photosynthate supply during flowering and early seed development.

Studies on the nitrogen and water relations of wheat

The interrelations between nitrogen and water supply on the growth and yield of wheat (Triticum aestivum L.) were studied with particular attention to water use and grain yield in relation to the time of application of nitrogen to the plants. Nitrogen was applied at seeding or deferred until the double ridge-stage of development. Effects of both soil-applied and foliar-applied nitrogen were investigated under deficient or adequate water supply. The supply of water to the crop controlled the level of yield obtained and the response of the crop to applied N was markedly greater in drought-free conditions. Application of N resulted in increases in both crop leaf area duration and water use. Greater responses to N were obtained when the fertilizer was applied to the soil, rather than as a foliar spray.

Influence of soil applications of nitrogen on nitrate reductase activity, leaf and grain protein content in sorghum

Three sorghum genotypes, L.187, SK5912 and RCFA×L.187 (the latter being a hybrid) were field grown under four nitrogen application rates and replicated four times. The experiments were of complete randomized plot design and conducted in 1976, 1977 and 1978.

Comparison of Urea Foliar Sprays Containing Hydrocarbon or Silicone Surfactants with Soil-applied Nitrogen in Maintaining the Leaf Nitrogen Concentration of Prune Trees1

Abstract The ability of urea foliar sprays containing hydrocarbon or silicone surfactants to maintain leaf N concentration in mature prune (Prunus domestica L.) trees was tested in a non-irrigated commercial orchard near Young, New South Wales. In 1976-77, foliar-applied N was as effective in maintaining leaf N concentration as soil-applied N on a g for g N basis, but a silicone surfactant which enabled sprays to completely wet leaves and to spontaneously penetrate open stomata, was no more effective in terms of leaf N concentration than a conventional hydrocarbon surfactant. In 1977-78, a drought year, foliar-applied N was more effective than soil-applied N. However, the silicone surfactant was less effective than the hydrocarbon, as run-off was excessive and the spray film dried very rapidly. Inclusion of the humectant glycerol in the silicone sprays retarded the rate of drying and eliminated the difference between the surfactants. A combination of soil and foliar N is suggested as a means of maximizing control of tree N status in most years. However, conventional surfactants appear to be slightly superior to silicone surfactants in high-volume spraying.

Response of Rice to Foliar and Soil Application of Nitrogen.

The response of rice IR 20 and Ponni to foliar vs. soil application of nitrogen was studied for two years. Five treatment combinations of nitrogen were tried with soll and foliar applications. In both paddy varieties foliar application was significantly supe- rior to the other treatments.

Interrelations between nitrogen and phosphorus fertilization and early blight control of potatoes

Three different rates of soil-applied nitrogen were combined in all possible combinations with different schedules of fungicidal sprays for early blight (Alternaria solani) control in field experiments for three consecutive years. The nitrogen was applied with a constant rate of phosphorus. Yield response to fungicidal sprays was more pronounced when potato plants had received nitrogen and phosphorus. Both spraying and fertilizer application reduced the percentage of leaflets infected by early blight. However, the effect of the fungicide was greater than that of fertilizers. Estimates based on the cost and price assumptions indicated that $1.00 investment in the optimum number of fungicidal sprays at the adequate rate of fertilizer returned $8.34, $9.71 and $1.89 in 1970, 1971 and 1972, respectively.

A preliminary study on the use of rapid chemical tests as aids in diagnosing nutrient deficiencies in the Irish Potato

1. The effects of soil applications of nitrogen, phosphorus, and potash fertilizers on the soluble nutrient content of potato leaf petioles and on yields of tubers were studied. Rapid tissue tests were used to determine the nutrient content of leaf petioles at successive intervals during the growing season. 2. Soil applications of nitrogen fertilizer at the rate of 80 pounds or 160 pounds per acre approximately doubled the N content of potato leaf petioles and doubled the yields of tubers. The concentrations of soluble P and K2O were found to be inversely correlated with the soluble N content of potato leaf petioles. 3. Soil applications of phosphate fertilizer had no effect on yields of tubers, nor on soluble N content of potato leaf petioles. Under conditions of high N supply, application of phosphate fertilier resulted in significantly higher P content and in slightly lower soluble K2O content of leaf petiole tissues. 4. Soil applications of potash fertilizer had no effect on yields of tubers nor on the soluble N content of potato leaf petioles. Under conditions of high N supply, application of potash fertilizer resulted in significantly higher soluble K2O content but had no effect on soluble P content of leaf petiole tissues. 5. Under the conditions of this experiment, the maximum yields were obtained when the soluble N content of the leaf petioles at the time of first visible flower buds were 600–700 p.p.m.; the soluble P content was 300–400 p.p.m.; and the soluble K2O was 4200–6200 p.p.m.