Long-Term Effects of Nitrogen Fertilizer Use on Ground Water Nitrate in Two Small Watersheds

2003 ◽  
Vol 32 (6) ◽  
pp. 2158-2171 ◽  
Author(s):  
M. D. Tomer ◽  
M. R. Burkart
Keyword(s):  
Ground Water ◽  
Nitrogen Fertilizer ◽  
Long Term Effects ◽  
Fertilizer Use ◽  
Small Watersheds

Alternative production systems to reduce nitrates in ground water

1987 ◽  
Vol 2 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Robert I. Papendick ◽  
Lloyd F. Elliott ◽  
James F. Power
Keyword(s):  
Ground Water ◽  
Nitrogen Fertilizer ◽  
Cover Crops ◽  
Production Systems ◽  
Root Zone ◽  
Conservation Tillage ◽  
Current Status ◽  
Water Protection ◽  
Fertilizer Use ◽  
Nitrate Concentrations

AbstractEvidence indicates a strong positive relationship between increases in nitrogen fertilizer use on cropland and nitrate concentrations in shallow ground water. This raises concern about the fate and efficiency of nitrogen fertilizer with current farming practices. Approximately 50 percent of the nitrogen fertilizer applied may be recovered by agronomic crops and 35 percent or less removed in the harvested grain of a crop such as corn. The residual nitrogen is subject to loss by several processes, one being leaching from the crop root zone. Alternative production systems that provide ground water protection must give attention to improved management of nitrogen fertilizer and to practices that minimize the need for nitrogen fertilizer and reduce soil nitrate concentrations. Most important in nitrogen fertilizer management is to more closely match nitrogen availability in the soil with crop needs and to avoid over-fertilization. Nitrogen fertilizer use can be reduced by alternate cropping of low and high nitrogen-demanding crops, use of legumes in the crop rotation to fix nitrogen, and proper use of manures, crop residues, and other organic wastes. Residual nitrates in soil can be reduced by use of cover crops, nitrogen-scavenging crops in the rotation, and alternating shallow and deep-rooted crops. Conservation tillage alone as used with many conventional cropping systems will probably not change the current status of nitrate leaching. Practices used by organic farmers should be carefully studied as possible approaches for ground water protection and adaptation into conservation tillage systems for conserving soil and water resources.

Long-Term Effects of Mineral Nitrogen Fertilizer on Irrigated Maize and Soil Properties

2017 ◽  
Vol 109 (5) ◽  
pp. 1880-1890 ◽  
Author(s):  
E. Martínez ◽  
A. Maresma ◽  
A. Biau ◽  
S. Cela ◽  
P. Berenguer ◽  
...  
Keyword(s):  
Soil Properties ◽  
Nitrogen Fertilizer ◽  
Mineral Nitrogen ◽  
Long Term Effects

scholarly journals Long-term reduction of nitrogen fertilizer use through knowledge training in rice production in China

2015 ◽  
Vol 135 ◽  
pp. 105-111 ◽  
Author(s):  
Jikun Huang ◽  
Zhurong Huang ◽  
Xiangping Jia ◽  
Ruifa Hu ◽  
Cheng Xiang
Keyword(s):  
Nitrogen Fertilizer ◽  
Rice Production ◽  
Fertilizer Use

scholarly journals Effect of Composts and Synthetic Nitrogen Fertilizer on Growth and Nematode Infestation in Lettuce and Basil

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 864F-864
Author(s):  
Hector R. Valenzuela ◽  
Randall Hamasaki
Keyword(s):  
Nitrogen Fertilizer ◽  
Growth Cycle ◽  
N Fertilizer ◽  
Growth Yields ◽  
Long Term Effects ◽  
Compost Treatment ◽  
Synthetic Nitrogen Fertilizer

Experiments were conducted to evaluate the effect of two different compost materials and several compost: synthetic N fertilizer ratios on the growth, yields, and nematode infestations in head and semi-head lettuce, and basil. Treatments were homemade compost at 25 MT/ha, Amend compost at 25 MT/ha, N alone at 150 kg·ha–1, and Amend compost at 25 MT/ha plus 0, 100, 200 or 300 kg N/ha. The basil trial followed the lettuce experiment on the same treatment beds to evaluate the long-term effects of compost applications. Compost plus 100 kg N/ha resulted in the greatest yields of 12 to 24 MT/ha for the semi-head and head lettuce trials, respectively. Basil was harvested for 6 months during a 10-month growth cycle. Highest basil yields of 64 MT/ha and canopy growth were obtained with a combination of compost plus synthetic N fertilizer, with 300 kg N/ha required for maximum yields during the 6-month harvesting period. By the last sampling date nematode counts were lowest for plots that received compost treatment alone and highest for the controls and for plants receiving synthetic N fertilizer alone.

Long-term Effects of the Continuous Cultivation of a Tropical Ultisol in Southwestern Nigeria

1989 ◽  
Vol 25 (2) ◽  
pp. 207-215 ◽  
Author(s):  
A. Olu Obi
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Nitrogen Fertilizer ◽  
Continuous Cultivation ◽  
Continuous Cropping ◽  
Long Term Effects ◽  
Southwestern Nigeria ◽  
Continuous Use ◽  
Exchange Acidity

SUMMARYContinuous cropping of a tropical Ultisol with or without nitrogen fertilizer increased soil acidification and reduced soil organic matter and productivity. Addition of nitrogen fertilizer failed to increase yields. This was apparently due to the decline in soil pH, an increase in the amount of soluble aluminium, and consequent inefficient utilization of added nutrients. Continuous use of ammonium sulphate as a nitrogen source hastened the development of both surface and subsoil exchange acidity.

Ovarian Dysfunction in Fetally Irradiated Beagles

1977 ◽  
Vol 35 ◽  
pp. 658-659
Author(s):  
T. M. Seed ◽  
M. H. Sanderson ◽  
D. L. Gutzeit ◽  
T. E. Fritz ◽  
D. V. Tolle ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Low Dose ◽  
Long Term Effects ◽  
Ovarian Dysfunction ◽  
Dose Rates ◽  
Highly Sensitive ◽  
Microscopic Evaluation ◽  
Ovarian Pathology ◽  
Normal Offspring

The developing mammalian fetus is thought to be highly sensitive to ionizing radiation. However, dose, dose-rate relationships are not well established, especially the long term effects of protracted, low-dose exposure. A previous report (1) has indicated that bred beagle bitches exposed to daily doses of 5 to 35 R 60Co gamma rays throughout gestation can produce viable, seemingly normal offspring. Puppies irradiated in utero are distinguishable from controls only by their smaller size, dental abnormalities, and, in adulthood, by their inability to bear young.We report here our preliminary microscopic evaluation of ovarian pathology in young pups continuously irradiated throughout gestation at daily (22 h/day) dose rates of either 0.4, 1.0, 2.5, or 5.0 R/day of gamma rays from an attenuated 60Co source. Pups from non-irradiated bitches served as controls. Experimental animals were evaluated clinically and hematologically (control + 5.0 R/day pups) at regular intervals.

Ultrastructural investigations of MDL 19,660-induced effects on the canine platelet and megakaryocyte

1990 ◽  
Vol 48 (3) ◽  
pp. 374-375
Author(s):  
D.E. Loudy ◽  
J. Sprinkle-Cavallo ◽  
J.T. Yarrington ◽  
F.Y. Thompson ◽  
J.P. Gibson
Keyword(s):  
Antidepressant Drug ◽  
Beagle Dogs ◽  
Long Term Effects ◽  
Short Term ◽  
Platelet Counts ◽  
Toxicological Studies ◽  
Induced Aggregation ◽  
Internal Architecture

Previous short term toxicological studies of one to two weeks duration have demonstrated that MDL 19,660 (5-(4-chlorophenyl)-2,4-dihydro-2,4-dimethyl-3Hl, 2,4-triazole-3-thione), an antidepressant drug, causes a dose-related thrombocytopenia in dogs. Platelet counts started to decline after two days of dosing with 30 mg/kg/day and continued to decrease to their lowest levels by 5-7 days. The loss in platelets was primarily of the small discoid subpopulation. In vitro studies have also indicated that MDL 19,660: does not spontaneously aggregate canine platelets and has moderate antiaggregating properties by inhibiting ADP-induced aggregation. The objectives of the present investigation of MDL 19,660 were to evaluate ultrastructurally long term effects on platelet internal architecture and changes in subpopulations of platelets and megakaryocytes.Nine male and nine female beagle dogs were divided equally into three groups and were administered orally 0, 15, or 30 mg/kg/day of MDL 19,660 for three months. Compared to a control platelet range of 353,000- 452,000/μl, a doserelated thrombocytopenia reached a maximum severity of an average of 135,000/μl for the 15 mg/kg/day dogs after two weeks and 81,000/μl for the 30 mg/kg/day dogs after one week.

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