«University of California Division of Agriculture and Natural Resources Committee of Experts on Dairy Manure Management September 2003 February 2004, ...»
2-043-300-0 Calif. State Water Resour. Control Board, Sacramento.
Letey, J., Vaux, Jr., H.J., Fienerman, E., 1984. Optimum crop water application as affected by uniformity of water infiltration. Agron. J. 76, 435-444.
Newton, G. L., Johnson, Jr., J.C., Davis, J.G., Vellidis, G., Hubbard, R.K., Lawrance, R., 1995.
Nutrient recoveries from varied year round applications of liquid dairy manure or sprayfields. In: Proc. 32nd Annual Florida Dairy Production Conf., Gainesville, FL 11-12 Apr. 1995. Dairy Sci. Dep., CES, IFAS, Gainesville, FL. pp. 113-122.
Pang, X.P., Letey, J., 1998. Development and evaluation of ENVIRO-GRO, and integrated water, salinity, and nitrogen model. Soil Sci. Soc. Am. J. 62, 1418-1427.
Pang, X.P., Letey, J., 2000. Organic farming: Challenge of timing nitrogen availability to crop nitrogen requirements. Soil Sci. Soc. Am. J. 64, 247-253.
E-12 Sexton, B.T., 1993. Influence of nitrogen and irrigation management on corn and potato response and nitrate leaching. M.S. Thesis. Univ. of Minnesota, St. Paul.
Stanford, G., Frere, M.H., Schwaniger, D. H., 1973. Temperature coefficient of soil nitrogen mineralization. Soil Sci. 115, 321-323.
Van Kessel, J. S., Reeves III, J.B., 2002. Nitrogen mineralization potential of dairy manures and its relationship to composition. Biol. Fertil. Soils. 36, 118-223.
Vellidis, G., Davis, J., Lawrance, R., Williams, R., 1993. Soil water nutrient concentrations in the vadose zone of a liquid dairy manure land application site. In:1993 Int. Winter meeting, Chicago. 14-17 Dec. 1993. Am. Soc. Agric. Eng. St. Joseph MI. Paper no. 93Woodard, K. R., French, E.C., Sweat, L.A., Graetz, D.A., Sollenberger, L. E., Besoondat, B., Portier, K.M., Wade, B.L., Rymph, S.J., Prine, G. M., Van Horn, A. H., 2002. Nitrogen removal and nitrate leaching for forage system receiving dairy effluent. J. Environ. Qual.
Figure 2. The organic N mineralization rate as a function of time for five years when the time and amount of organic N application was biweekly to meet 70 percent of the potential N uptake and the half-life was 280 days during the summer.
The results for years greater than 5 are identical to the fifth year results.
Figure 3. The relative yield of corn (C), and forage (F) and the amount of nitrate-nitrogen leached during individual crop seasons as depicted over a ten-year period under uniform irrigation.
The lagoon water was applied each irrigation with the total N equal to 1.2 times the potential N uptake. The results are depicted for summer time half life mineralization rates of 90 and 280 days.
Figure 4. The relative yield of corn (C), and forage (F) and the amount of nitrate-nitrogen leached during individual crop seasons as depicted over a ten-year period under uniform irrigation.
The lagoon water was applied three times during the growing season with the total N equal to 1.2 times the potential N uptake. The results are depicted for summer time half life mineralization rates of 90 and 280 days.
Figure 5. The relative yield of corn (C), and forage (F) and the amount of nitrate-nitrogen leached during individual crop seasons as depicted over a ten-year period under uniform irrigation.
Only organic N was applied three times during the growing season with the total N equal to 1.2 times the potential N uptake. The results are depicted for summer time half life mineralization rates of 90 and 280 days.
1.5 1.0 0.5
N Use Efficiency can be expressed in various forms, but in general refers to crop recovery (either as plant uptake or harvested product) of N inputs to the crop-soil system.
Many studies of crop N recovery have been published in the scientific literature. Most encompass only one season; few studies of multi-year recovery have been conducted.
Lund et al. (1978) conducted a 12-year investigation on the N utilization efficiency in commercial vegetable production fields in Santa Maria Valley of California. They developed an N balance showing that 30% of the applied N was removed in the harvested crops, 37% was leached below the root zone, and 33% was unaccounted for, which was attributed mainly to gaseous loss of N due to denitrification. With a crop harvest N removal of 30%, an application of 3.33 times (333%) times harvest N removal would be required. If nitrate leaching were eliminated, the N input could be reduced by 37% (i.e., the leached N) and the applied N requirement from all sources would be 1.49 times (149%) of harvest N removal.
Broadbent and Carlton (1979) conducted field experiments on fertilizer N use efficiency under irrigated cropping conditions in Davis, CA and the UC Kearney Agriculture Center near Fresno, CA, using 15N-labelled fertilizer. They reported that applied N recovery ranged from 35 to 68% at the Fresno site and from 30 to 67% at Davis, with maximum recovery occurring at application rates that produced maximum grain yield. Very little nitrate derived from fertilizer escaped from the root zone unless fertilizer rates were in excess of crop needs. They concluded that “the potential for excess nitrate in the profile rises sharply above the optimum N fertilization rate.” They also concluded that “optimum production of corn is compatible with minimum pollution hazard with careful management of fertilizer and irrigation.” Under the circumstances, the N input requirements from all sources corresponding to the agronomic rates would be those with the highest fertilizer N recovery rates, calculated to be 148%.
Bock and Hergert (1991) provided general guidelines for unit N fertilization (e.g., N input per bushel harvested grain) based on assumed fertilizer N recovery by the aboveground crop. They recommended that the fractional fertilizer N recovery by upland cereal grains should be set at 0.45 when timing of applications was poor, 0.60 for medium efficiency, and 0.70 in highly efficient situations. Their definition of efficiency referred only to commercial N fertilizers applied in the year of crop production and did not include N derived from mineralization of soil organic matter, crop residues, or organic amendments like manure. From the minimum N rates required for maximum yield, Bock and Hergert (1991) derived the criteria in Stanford (1973) that 50 to 70% recovery of applied N is physically possible in most soil-plant systems, and up to 30 to 50% of applied N can be immobilized during decomposition of corn stover and roots if that much inorganic N remains in the root zone at the end of the growing season (Bock, 1984).
F-1 Based on Bock and Hergert (1991) and Stanford (1973) the agronomic rate again is approximately 140% of the crop N requirement.
Raun and Johnson (1999) estimated that worldwide, N use efficiency for cereal production (rice, wheat, corn, barley, millet, oats, and rye) is approximately 33%. They compared estimates of worldwide fertilizer N use on cereal grains and estimates of N removed in harvested grain. They did not include as inputs soil N obtained from biological N fixation (e.g., when cereals are grown in rotation with legumes) or miscellaneous other sources such as direct deposition of atmospheric N and nitrate contained in irrigation water. Based on their analysis, it is possible only to state that the long-term N removed worldwide by harvests of cereals amounts to between one-third and two-thirds of all externally derived N inputs. Based on this set of data, the N input requirement (from all sources) for cereal production, based on the average N recovery percentage, is 150 to 300% of harvest removal.
A few N recovery studies have been conducted in manured systems. It is much more difficult to label manure N with the tracer 15N than to do so with synthetic inorganic fertilizers. In a three-year study with potted plants using 15N-labelled poultry manure, the N recovery by cereals ranged from 19 to 36% (fresh manure), 17 to 24% (anaerobically incubated) or 12 to 14% (aerobically incubated). On average, 62% of manure N was found in the soil after three years. Gaseous losses ranged from 7 to 26% of N (Kirchmann, 1989). It appeared that the recovery of organic-borne N by plants was consistently lower than from chemical fertilizers and the remainder of the added N accumulated in the soils.
Powlson et al. (1991) conducted 15N-labelled fertilizer trials in Rothamsted Station, UK and reported that 50 to 80% of fertilizer N was found in the harvested crop and 10 to 25% in soil. It was noted that most of the labeled N was in organic forms, not as “left- over” fertilizer N. Long-term studies at Rothamsted Station, UK, on a silty clay loam and a sandy loam, showed that more than 89 lbs N acre-1 yr–1 (100 kg N ha-1 yr-1) were lost from soils when large applications of animal manure, sewage sludge and composts were being applied (Addiscott et al., 1991). The mineralization of organic N over time increases soil N and correspondingly decreases the nitrogen input requirement.
The Sustainable Agriculture Farming Systems (SAFS) project at UC Davis provided multi-year crop N recovery estimates for irrigated cropping systems employing animal manure applications. The crop rotations include processing tomato, corn for grain, wheat for grain, and green manure legume crops. An organic farming system was compared to two-year and four-year conventional rotations and a low-input system. The organic system relied on manure and legume cover cropping for N supply. Poudel et al. (2001) evaluated the N balance for the first 10 years of the SAFS project. N inputs and crop harvest removal of N were higher in the conventional systems than in the organic system.
The apparent N recovery was 48% in the organic system, 71% in the conventional twoyear rotation, and 73% in the conventional four-year rotation. Thus, in the organic system, more than 2 lbs N were added from all sources for each pound of N removed in the harvested crop, compared to an input of 1.4 lbs N for each pound harvested in the F-2 conventional systems. However, the apparent N recovery was not related to the amount of N leached in each treatment. The annual loss of N averaged over 10 years was 8 lbs N acre-1 yr-1 (9 kg ha-1 yr-1) in the organic system, while in the conventional four-year rotation treatment it was 37 lbs N acre-1 yr-1. In the organic system, the buildup of soil organic N averaged 80 lbs N acre-1 yr-1 (90 kg ha-1 yr-1) much higher than the annual 7 lbs N acre-1 yr-1 (8 kg ha-1 yr-1) buildup in the conventional four-year rotation treatment.
While the organic system appeared much less efficient than the conventional four-year rotation in terms of N recovery by crops (apparent N recovery of 48% vs. 73%), the nitrate leaching was much lower in the organic system due to the increase of soil organic matter and the accompanying build-up of soil organic N. However, the build-up cannot continue indefinitely. At some point, a steady state will be reached, and the net N mineralization of soil organic matter will increase to the point that annual N inputs can be reduced, thus increasing the apparent N recovery for that system. Note that the organic farming system in the SAFS study received considerably lower amounts of organic N than do dairy forage fields in the San Joaquin Valley (Harter et al., 2001).
Bock, B.R. and G.W. Hergert. 1991. Fertilizer nitrogen management. p. 139-164. In R.F.
Follett, D.R. Keeney, and R.M. Cruse (eds.) Managing nitrogen for groundwater quality and farm profitability. Soil Sci. Soc. Amer. Madison, WI.
Bock, B.R., 1984. Efficient use of N by cropping systems. p. 273-293. In R.D. Hauck (ed.) Nitrogen in crop production. ASA, CSSA, and SSSA, Madison, WI.
Broadbent, F.E. and A.B. Carlton. 1979. Field trials with isotopes – plant and soil data for Davis and Kearney sites. p. 433-465. In Pratt, P.F. Nitrate in effluents from irrigated lands. Final report to the National Science Foundation. PB-300582, US Dept. of Commerce, National Technical Information Service, Springfield, VA.
Kirchmann, H. 1989. A 3-year N balance study with aerobic and fresh 15N-labelled poultry manure. p. 113-139. In J.A. Hansen, J.A and K. Kenriksen, (ed.). Nitrogen in organic wastes applied to soils. Academic Press, San Diego, CA.
Lund, L.J., J.C. Ryden, R.J. Miller, A.E. Laag, and W.E. Bendixen. 1978. Nitrogen balances for the Santa Maria Valley. p. 395-413 In P.F. Pratt (ed.) Proceedings national conference on management of nitrogen in irrigated agriculture. Dept. of Soil & Environmental Sciences, University of California, Riverside CA.
Poudel, D.D., W.R. Horwath, J.P. Mitchell, and S.R. Temple. 2001. Impacts of cropping systems on soil nitrogen storage and loss. Agric. Systems 68:253-268.
Powlson, D.S., P.B.S. Hart, P.R. Poulton, A.E. Johnston, and D.S. Jenkinson. 1992. The influence of soil type, crop management and weather on the recovery of 15N-labelled fertilizer applied to winter wheat in spring. J. Agric. Sci. 118(1):83-100.
Raun, W.R. and G.V. Johnson. 1999. Improving nitrogen use efficiency for cereal production. Agron. J. 91:357-363.
Stanford, G., M.H. Frere, and D. H. Schwaninger. 1973. Temperature coefficient of soil nitrogen mineralization. Soil Sci. 115: 321-323.
Under conventional practices (no specific manure nutrient management), Harter et al.
(2002) estimated that the nitrate N and dissolved salt loading from five dairies in the northeastern Central Valley (Merced and Stanislaus County) averaged 280 and 4,300 kg ha-1 yr-1, respectively. These estimates are based on direct measurements of shallow groundwater known to originate primarily from the dairies and their surrounding fields.