Nitrogen Use Efficiency in Crop Plants - Nitrogen Management in Crop Production - page 228

receiving 50, 100, and 150 kg N ha −1 was 34%, 38%, and 25%, respectively. Similarly, Stevens
et al. (1996) reported that the N recovery efficiency by cotton was 38%, 28%, 19%, and 9% at
rates of 45, 90, 135, and 180 kg N ha −1 . Constable and Rochester (1988) reported an N recovery
efficiency of 30% for irrigated cotton grown on Vertisols. Wienhold et al. (1995) reported that
corn grain utilized 35% and stover an additional 15% of the applied N fertilizer, while 30% of
the N remained in the upper 0.6 m of the soil profile at the end of the growing season. Novoa
and Loomis (1981) reported that, in calculating ARE, the majority of miscalculation is to do
with basing the recovery estimate on grain N alone, ignoring the N accumulated into roots and
straw residues, which recycles to soil humus and thus is available to subsequent crops. Fageria
et al. (2011) compiled data from various sources and reported that AREs for major cereals in
different continents are less than 50% (Table 5.6). In addition, the ARE was in the order of
rice > wheat > corn = millet > sorghum.
Several authors have reported that current practices of N fertilizer management are often very
inefficient as compared to natural systems, thus increasing the potential for N losses in crop pro-
duction (Sanchez and Blackmer, 1988; Randall et al., 1997; Cambardella et al., 1999; Dinnes et al.,
2002). As a result, first year recoveries of fertilizer N by corn have been reported to be 35%
(Bijeriego et al., 1979), 14-65% (Meisinger et al., 1985), 23-45% (Kitur et al., 1984), 24-26%
(Olson, 1980), 15-33% (Sanchez and Blackmer, 1988), and 45-59% (Reddy and Reddy, 1993).
Approximately 28-55% of the N applied is taken up by the crop (Bundy and Andraski, 2005).
Fertilizer recovery typically decreases with an increase in N application rate, and farmers incur
economic loss by applying more N than is required to obtain a positive yield response (Macdonald
et al., 1989).
Globally, a large land area is under pasture as compared to crop production. Hence, the knowl-
edge of N recovery under pasture is very important. Schepers and Mosier (1991) reported that N
recovery in pastures varies from 50% to 65% of the total N applied through N fertilizer. The N
dynamics, at the site under grazing, with N application (urine) between 200 and 250 kg N ha −1 year −1
showed that one-third of the total applied N was retained by organic matter (25%) and by the plant
root system (2-5%). Of the remaining N, a part is lost by ammonium volatilization after applica-
tion (20%), ammonia volatilization from the spots of excreta deposition (20-30%), denitrification
(6-12%), and by leaching or other types of losses, such as excretion outside the pasture (20-50%).
Another fraction goes into animal production, be it meat (7-9%) or milk (14-18%) (Kimura and
Kurashima, 1991; Whitehead, 2000).

TABLE 5.6
Average Apparent Recovery Efficiency (%) of Nitrogen for Five Major Cereals in Various
Continents

Continent Millet Sorghum Maize Rice Wheat

Europe 40 (3) 48 (34)

Africa 40 (25) 45 (6) 51 (11) 28 (30) 39 (4)

Asia 40 (4) 38 (9) 41 (12) 39 (66) 45 (22)

North America 18 (4) 29 (22) 53 (1) 51 (4)

South America 32 (9) 32 (42) 55 (17) 34 (32)

Australia 35 (9) 45 (3) 50 (9) 43 (12)

Average 40 34 40 45 43

Source: From Fageria, N. K., V. C. Baligar, and C. A. Jones. 2011. Growth and Mineral Nutrition of Field Crops , 3rd edi-
tion. Boca Raton, Florida: CRC Press. With permission.)
Note: Values in brackets are number of observations.