Nitrogen Fertilization of No-Tillage Winter Cereals in the ... - Scielo.br

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Rev Bras Cienc Solo 2017;41:e0170009

Division - Soil Use and Management | Commission - Soil Fertility and Plant Nutrition

Nitrogen Fertilization of No-Tillage Winter Cereals in the South-Central Region of Paraná, Brazil Sandra Mara Vieira Fontoura(1), Fernando Viero(2), Renato Paulo de Moraes(1) and Cimélio Bayer(3)* (1)

Fundação Agrária de Pesquisa Agropecuária, Guarapuava, Paraná, Brasil. Universidade Federal do Rio Grande do Sul, Departamento de Ciência do Solo, Programa de PósGraduação em Ciência do Solo, Porto Alegre, Rio Grande do Sul, Brasil. (3) Universidade Federal do Rio Grande do Sul, Departamento de Ciência do Solo, Porto Alegre, Rio Grande do Sul, Brasil. (2)

* Corresponding author: E-mail: [email protected] Received: January 11, 2017 Approved: May 16, 2017

How to cite: Fontoura SMV, Viero F, Moraes RP, Bayer C. Nitrogen fertilization of notillage winter cereals in the south-central region of Paraná, Brazil. Rev Bras Cienc Solo. 2017;41:e0170009.

ABSTRACT: High winter cereal yields depend on an adequate supply of nitrogen (N). We developed a system for indicating N rates for wheat and barley in the South-Central region of the state of Paraná, Brazil, using results of 72 field experiments conducted from 2007 to 2012. The N rates recommended for winter cereals were estimated to supply the amounts of N fertilizer needed to obtain increasing yields (5.5 Mg ha-1) of crops grown after soybean and corn on soils with a variable organic matter content (60 g dm-3). The apparent mineralization rate of soil N was estimated to be 1 % and the N fertilization efficiency 50 %. The N rates recommended for wheat ranged from 30 to 150 kg ha-1 when cultivated after soybean, and from 30 to 170 kg ha-1 after corn. The N rates for barley ranged from 30 to 120 kg ha-1 when grown after soybean, and from 30 to 130 kg ha-1 after corn. These N rates are consistent with those indicated by the Soil Fertility Commission for the states of Rio Grande do Sul and Santa Catarina (CQFS-RS/SC, 2016), and also with the rates of maximum economic efficiency estimated in our study. The proposed N rate recommendation system can be used by agricultural technicians and producers to manage N fertilization of wheat and barley in the South-Central region of Paraná, Brazil. Keywords: Triticum aestivum, Hordeum vulgare L., N indication, urea.

https://doi.org/10.1590/18069657rbcs20170009

Copyright: This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided that the original author and source are credited.

http://doi.org/10.1590/18069657rbcs20170009

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Fontoura et al. Nitrogen fertilization of no-tillage winter cereals in the south-central…

INTRODUCTION Winter cereals grown in rotation with soybean (Glycine max L.) or corn (Zea mays L.) in the South-Central region of Paraná, Brazil, cover an area of approximately 60,000 ha, cultivated exclusively under no-tillage (Fontoura et al., 2015). Roughly one-half of the acreage produces wheat (Triticum aestivum L.) and the other half barley (Hordeum vulgare L.), with a mean yield of around 5,000 kg ha-1 (Agrária, 2016). However, grain yield in both crops in experimental areas managed by the Fundação Agrária de Pesquisa Agropecuária (FAPA) in Guarapuava-PR is as high as 9,000 kg ha-1, which testifies to the high productive potential of these cereals in the region and demonstrates a marked yield difference between experimental sites and farmers’ fields. Grain productivity depends not only on the use of productive varieties, and suitable phytosanitary and weed control measures (Benin et al., 2012), but also on an adequate supply of nutrients (particularly nitrogen N) (De Bona et al., 2016). However, the lack of recommendation systems to facilitate efficient N fertilization in some Brazilian regions has led to poorer cereal responses to N fertilization and lower profitability relative to other crops such as corn. The N rates recommended for wheat in the states of Mato Grosso do Sul and São Paulo are based on grain yield expectations and the preceding crop (Minella, 2015). However, in the states of Rio Grande do Sul and Santa Catarina, the estimated N rates also consider the organic matter content, which is related to the potential of the soil to supply the crops with N (CQFS-RS/SC, 2016). The South-Central region of Paraná lacks an official N recommendation system for winter cereals. Despite the high technology levels in regional agriculture, the recommended N rates for winter cereals have been based on average N rates established by technicians and producers or on recommendations extrapolated from other regions such as Rio Grande do Sul and Santa Catarina. As with corn (Fontoura and Bayer, 2009), a specific N recommendation system for winter cereals might increase the agronomic efficiency of N fertilizers while minimizing the potential impact of these nutrient inputs on the environment. In this study, we tested the hypothesis that N rates to be applied aiming to attain crescent grain yields of wheat and barley are also dependent on soil organic matter level and preceding summer crop. Our main objective was to develop an N recommendation system for wheat and barley in the South-Central region of Paraná that considers the preceding crop (soybean or corn), soil organic matter, and expected grain yield by examining the results of 72 field experiments performed from 2007 to 2012 in experimental areas managed by the FAPA.

MATERIAL AND METHODS Region description The South-Central region of Paraná is located on the third physiographic plateau of the state (Figure 1), 800 to 1,200 m a.s.l. The soils were derived from basalt and are predominantly Brown Latossol by Brazilian Classification (Fontoura et al., 2015) and clayey Hapludox (Soil Survey Staff, 2014). With regard to soil organic matter (OM), 59 % of the soils of the region managed by the Cooperativa Agrária Agroindustrial (Guarapuava, Paraná) contain 41-60 g dm-3 of OM, 16 % contain less than 40 g dm-3 of OM, and 25 % more than 60 g dm-3 of OM (Figure 1). The climate in the region is humid subtropical (Cfb according to Köppen system), with an average annual rainfall of 1,900 mm well distributed throughout the year, with no dry season; rainfall is lowest in August, coinciding with the period of N fertilizer topdressing on winter cereals. Based on data from the weather stations of the FAPA, monthly rainfall ranges from 145 to 220 mm, except in August, with about 100 mm only. The average annual temperature is 16.8 °C and monthly averages range from 12.6 °C in July to 20.3 °C in January (Figure 1).


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Rainfall (mm)

30 25 20 15 10

Rainfal T maximum T medium T minimum

200 160

Temperature (°C)


120 80 40 0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 59%

Frequency (%)

60 45 30 15 0

25% 16%

60

Soil organic matter (g dm-3)

Figure 1. Map of Southern Brazil and South-Central Paraná (in gray), where the experiments of N fertilization of winter cereals were conducted. Monthly rainfall and temperatures (maximum, medium, and minimum), and soil organic matter distribution (Fontoura et al., 2015) are shown.

Experiments The study was based on results of 72 experiments conducted from 2007 to 2012 by FAPA in areas cultivated under no-tillage for more than 20 years. In total, 52 experiments involved increasing rates of urea-N applied as topdressing to winter cereals cultivated in soybeancorn succession: 22 under wheat (Triticum aestivum L.) and 30 under barley (Hordeum vulgare L.) (Table 1). Another 20 experiments were conducted in 2008 and 2009, 10 with wheat and 10 with barley, in order to assess the N supply potential of the soils. The experiments were distributed in five sites (Guarapuava, Candói, Pinhão, Murakami, and Teixeira Soares) in the region managed by the Cooperativa Agrária Agroindustrial. The tables 2 and 3 show the chemical properties of the soils. The experiments were arranged in a randomized block design with four replications. The applied N fertilizer consisted of common urea, applied as topdressing between the sprouting and elongation stages, generally corresponding to the stage of 4 to 6 leaves on the main stem (Haun, 1973). The rates to obtain maximum economic efficiency (MEE) were calculated for those treatments where the response of crop yields to increasing N rates followed a polynomial behavior and were based on the average grain price from 2007 to 2012. The fertilizer : grain price ratio (price of kg of N per price of kg of grain) was 4.362 for wheat and 4.137 for barley [grain yield class I = grain yield × commercial classification (grain >2.5 mm)] (Brasil, 1996).


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Table 1. Preceding crops, N rates, and cultivars used in the N fertilization experiments of wheat and barley conducted from 2007 to 2012 in the South-Central region of Paraná, Brazil Year

Pre-crop

N rates kg ha

Cultivars

-1

Wheat 2007 2008 2009 2011 2012

Soybean Corn Soybean Corn Soybean Corn Soybean Soybean Corn

0, 30, 60, 90, and 120

BRS Guabijú, BRS Guamirim, Quartzo, Safira

0, 30, 60, 90, and 120

BRS Guabijú, BRS Guamirim, Quartzo, Safira

0, 30, 60, 90, and 120

BRS Guabijú, BRS Tangará, Campeiro, Quartzo

0, 30, 60, 90, and 120

Campeiro, TBio Iguaçu, TBio Mestre

0, 30, 60, 90, and 120

Campeiro, Tbio Iguaçú, Tbio Mestre Barley

2007 2008 2009 2011 2012


0, 20, 40, 60, 80, and 100

BRS Cauê, BRS Elis, BRS Yeda

0, 20, 40, 60, 80, and 100

BRS Cauê, BRS Elis, BRS Brau

0, 20, 40, 60, 80, and 100

BRS Cauê, BRS Elis, BRS Brau

0, 20, 40, 60, 80, and 120

BRS Brau, MN 6021, PFC 2006127

0, 20, 40, 60, 80, and 120

BRS Brau, MN 6021, BRS Korbel

Each pre-crop (soybean or corn) and cultivar represented an experiment in combination with the topdressed N fertilizer rate. Fifty-two experiments were carried out; in some years, not all cultivars were assessed with both pre-crops.

Table 2. Chemical properties of the soils where the nitrogen fertilization experiments with winter cereal crops were conducted in the South-Central region of Paraná Year

2007 2008 2009 2011 2012

2007 2008 2009 2011 2012

Pre-crop

OM g dm-3


47 48 49 49 60 50 56 52 46

Soybean Corn Soybean Soybean Corn Soybean Soybean Corn

47 48 49 60 50 56 52 46

pH(CaCl2) Wheat 4.8 4.8 5.0 5.4 5.5 5.1 5.0 5.1 4.9 Barley 4.8 4.9 5.1 5.5 5.1 4.9 5.1 4.9

P mg dm-3

K+ cmolc dm-3

V %

10.0 13.9 8.7 9.4 15.3 9.3 14.0 8.6 9.6

0.34 0.24 0.27 0.32 0.71 0.37 0.37 0.19 0.27

52 55 62 67 67 58 50 55 46

10.0 13.0 9.4 17.1 9.3 11.2 8.6 8.6

0.34 0.24 0.28 0.73 0.37 0.30 0.19 0.27

52 54 62 66 57 45 55 46

+

OM: soil organic matter (Walkley-Black); P: available phosphorus (Mehlich-1); K : exchangeable potassium (Mehlich-1); V: base saturation. Experiments with different wheat and barley cultivars following soybean or corn (Table 1) were conducted each year.


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Table 3. Soil chemical properties in the South-Central region of Paraná where the experiments to determine the apparent N mineralization from soil organic matter were conducted Experimental site

SOM g dm

pH(H2O)

K+

P

-3

mg dm

-3

cmolc dm

V -3

%

2008 Guarapuava

61

5.7

6.6

0.42

62

Candói

59

5.4

4.5

0.33

50

Pinhão

62

5.9

4.9

0.40

71

Teixeira Soares

39

5.9

8.0

0.39

59

2.6

0.20

43

2009 Candói

50

5.2

Guarapuava 1

45

6.3

8.6

0.45

84

Guarapuava 2

48

5.5

8.2

0.53

52

Murakami

52

6.0

4.5

0.54

77

Pinhão

44

5.9

4.0

0.65

69

Teixeira Soares

34

5.2

7.0

0.42

43

+

OM: soil organic matter (Walkley-Black); P: available phosphorus (Mehlich-1); K : exchangeable potassium (Mehlich-1); and V: base saturation.

Grain yield expectation ranges and N rates to be applied Expected yield ranges for wheat and barley were initially established from the overall grain yield for all experiments with increasing N rates. To the overall average, the standard deviation was added and subtracted, with appropriate rounding, adding two extreme values to the range. Thus, the expected yield ranges established for both cereals were 5.5 Mg ha-1. The mean grain yields of wheat and barley, and the average N rate required to obtain yields within each expectancy range were estimated from the results of the 52 experiments involving application of variable N rates to winter cereals cultivated after soybean or corn. Polynomial equations fitted with average N rates (axis X) and the mean yields (axis Y) estimated for the different expected yield ranges were used to calculate the N rates required to obtain the mean yields for the 3.5-4.5 and 4.5-5.5 Mg ha-1 ranges, as well as those for the 5.5 Mg ha-1 ranges, leading to yields of 3.0 and 6.0 Mg ha-1, respectively. Adjusting N rates for soils with different OM levels The previously estimated N rates correspond to the N recommendations for winter cereals on soils with OM levels from 41 to 60 g dm-3, this range of OM was present in the soils of all 52 experiments (Table 2). These N rates, [N recommendation(OM range 41-60 g dm-3)] were adjusted for the rates to be applied to soils with OM levels 60 g dm-3, considering the difference in the amount of mineralized N (Δmineralized) compared to the soils with OM levels of 40 to 60 g dm-3, and also for the efficiency of urea-N applied in the fertilizer (Ef aN), using equations 1 and 2. 1 ) Ef aN 1 N recommendation(OM range >60 g dm-3) = N rate(OM range 41-60 g dm-3) - (ΔNmineralized × ) Ef aN

N recommendation(OM range 60 g dm-3) and expected grain yield low (5.5 Mg ha-1) and low OM soils. Raising wheat yields above 5.5 Mg ha-1 would not only require an adequate N supply, but also the absence of restrictive management and environmental factors limiting crop development (Amado et al., 2002; Benin et al., 2012) such as plant diseases, weed infestation or water deficiency.

Table 4. Indicated urea-N rates for crescent yield expectations of wheat and barley cultivated in soils with different soil organic matter contents and preceding summer crops (corn or soybean) in the South-Central region of Paraná Pre-Crop/SOM

Expected grain yield Mg ha-1 5.5

Wheat (2,3) After soybean 60 g dm

-3

Barley

(2, 3, 4)

After soybean 60 g dm-3

60

80

100

120

30

50

70

90

30

30

40

60

70

90

110

130

40

60

80

100

50

70

After corn 60 g dm

(1)

-3

-3

30

(2)

30

-1

Soil organic matter in the 0.00-0.20 m layer. Total N rate (kg ha ). (4) recommended at seeding. Grain yield class 1 (Brasil, 1996).

(3)

-1

An application of 30 kg ha of N is


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The N rates recommended for barley (Table 4) ranged from 30 to 130 kg ha-1 and were 10 kg ha-1 higher when the crop was grown after corn than after soybean. As an exception, the N rates with both pre-crops were equivalent when barley was cultivated on soils with high OM contents and low grain yield expectations. Increases in the expected grain yield (grain yield class 1) required more N fertilizer: 30 to 60 kg ha-1 for the highest expected grain yield (>5.5 Mg ha-1) compared to the 60 g dm-3) and a low expected grain yield (