Agriculture Reference
In-Depth Information
TABLE 3.7 (continued)
Uptake of Macro- and Micronutrients by Upland Rice, Lowland Rice, Dry Bean, Corn, and
Soybean Grown on Brazilian Oxisols
Nutrient
Straw
Grain
Total
Required to Produce 1 t Grain b
Soybean
(3518 kg ha −1 ) a
(4003 kg ha −1 ) a
79
37.5
280.0
317.5
Nitrogen (kg ha −1 )
4
Phosphorus (kg ha −1 )
1.76
14.3
16.1
34
Potassium (kg ha −1 )
57.5
77.5
135.0
11
Calcium (kg ha −1 )
31.0
13.4
44.4
8
Magnesium (kg ha −1 )
20.3
10.2
30.5
50
Zinc (g ha −1 )
29.3
169.3
198.6
23
Copper (g ha −1 )
32.8
60.3
93.1
140
Iron (g ha −1 )
187.3
373.0
560.3
59
Manganese (g ha −1 )
117.4
120.1
237.5
Boron (g ha −1 )
22
21
43
Sources: Adapted from Fageria, N. K. 2001b. Rev. Bras. Eng. Agric. Ambiental . 5:416-424; Fageria, N. K., V. C. Baligar, and
R. W. Zobel. 2007. Commun. Soil Sci. Plant Anal . 38:1637-1653; Fageria, N. K., V. C. Baligar, and C. A. Jones.
2011a. Growth and Mineral Nutrition of Field Crops , 3rd edition. Boca Raton, Florida: CRC Press.
a Straw and grain yield.
b Accumulation in straw and grain (macronutrients in kg and micronutrients in g).
it is also required in large amounts to produce 1 metric ton of grain of all the five crops. In addition,
a large amount of N is accumulated in grains that cannot be recycled back to the soil. Hence, the
application of a large amount of N fertilizers is required to maintain the sustainability of cropping
systems or succeeding crops in rotation with these crops. Thompson et al. (1975) reported that each
ton of wheat grain contains 23 kg N. Bhatia and Rabson (1976) reported that, in rice, 10 kg N is
required to produce 1 ton of rice grain, whereas in wheat and rye, 16 kg N is required to produce 1
ton of grain. In an examination of 16 winter wheat varieties in the United Kingdom and France, the
N requirement per Mg grain ranged from 14.4 to 31.1 kg under low and high N treatments, respec-
tively (Gaju et al., 2011). Similarly, in an investigation of 10 winter wheat varieties in Mexico, the
requirement per Mg grain ranged from 23 to 37 kg (Ortiz-Monasterio et al., 1997). Liu et al. (2006)
reported that across widely differing environments in China, the average N requirement of winter
wheat was 25 kg for yields that ranged from 0.35 to 8.73 Mg ha −1 (Liu et al., 2006). Yue et al. (2012b)
reported that in winter wheat, for the optimum N fertilizer treatment, the average N requirement
was 24.3 kg per Mg grain yield and it declined with increasing grain yield. These authors further
reported that for the yield ranges between 6.0 and 7.5 Mg ha −1 , N requirement decreased from 27.1
to 24.5 kg due to the increasing harvest index (HI, from 0.39 to 0.46) and decreasing grain N con-
centration (from 2.41% to 2.21%).
Historically, N fertilizer recommendations for corn in the United States have been based on a
simplified empirical formula called the yield goal (Hoeft et al., 2000; Kyveryga et al., 2013). The
major premise of yield goal recommendations is that corn N requirements or optimum N rates
are proportional to corn yields, with a constant multiplier of 21.4 kg N Mg −1 corn grain. These
calculations were based on the assumption of a constant supply of N from the soil under a wide
range of soil and weather conditions (Kyveryga et al., 2013). While the yield goal recommenda-
tions were based on a mass balance approach (N rates should approximate N removed by grain
plus adjustments for N losses and N supplied by the soil). However, several studies have shown a
low correlation between corn yields and optimal N rates (Vanotti and Bundy, 1994; Scharf et al.,
2006). The low correlation is often attributed to the large variability in the N supply from the soil
 
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