EFFECTS OF APPLIED FERTILIZER AVERAGED OVER ROTATIONS 1 Wheat grain and straw, rain-water-use efficiency and δ 13 C

Nitrogen did not increase grain yield, or grain or total dry matter efficiency based on annual rainfall (RWUE grain and RWUE tot) at Jemaa Shaim, during the 2000–2001 growing season (Table IX).

Research in semi-arid Morocco has shown that whether to apply N-fertilizer is a dilemma because it may accelerate water deficit under severe drought conditions especially in the middle and at the end of the crop-growth cycle [38]. However, El Mejahed [4] found that a reasonable amount of applied N might only slightly affect water use but it increased WUE through increased dry-matter production before wheat-stem elongation.

Furthermore, many Moroccan farmers practice cereal–food legume and cereal–fallow rotations to compensate for low N-fertilizer application [39].

Table IX. Effects of nitrogen combinations on wheat yield, rain-water-use efficiency and carbon discrimination at Jemma Riah and Jemma Shaim, 1998–2002

Jemaa Riah Jemaa Shaim

Growing

season Parameter

0–40^a 40–0 40–46 0 0–40 40–0 40–46 0 Grain (kg/ha) 1,556 1,689 1,827 1,923 704 737 597 819

Straw (kg/ha) 2,976 2,913 2,548 2,563 2,984 3,246 3,008 3,087

RWUE gr (kg/ha/mm) 8.02 8.71 9.42 9.91 3.97 4.16 3.37 4.63

Straw (kg/ha) 2,183 2,233 2,261 2,050 1,962 1,970 2,001 1,831

RWUE gr (kg/ha/mm) 5.87 5.64 5.69 4.94 2.69b 2.11b 1.93b 3.03a

Straw (kg/ha) 1,298 1,408 1,347 1,406 4,700 4,313 4,429 4,504

RWUE gr (kg/ha/mm) 1.68 1.66 1.71 1.94 10.2 10.5 10.1 9.88

a Nitrogen treatments; see Materials and Methods.

3.2. Nitrogen uptake, percent nitrogen derived from fertilizer and nitrogen-use efficiency

The effects of N on these parameters was not consistent across years or locations. Nitrogen uptake by the grain (Nup grain) was highest in the check plot only at Jemaa Shaim in the 2000–2001 growing season. In the other situations, N uptake grain and straw (Nup straw) as well as total N uptake (Nup tot) were either not affected by applied N, as in 1999–2000 and 2001–2002 at Jemaa Riah, or increased with applied N, especially at the end of tillering or both at planting and at tillering (TableX).

Except for Jemaa Riah, where the lowest values for %Ndff for both grain and straw were obtained, dual N application at planting and the end tillering resulted in higher values than in the other treatments (Table X). Nitrogen use efficiency was not affected at Jemaa Riah in 1999–2000 or at Jemaa Shaim in 2000–2001 or at either location in 2001–2002. These parameters were highest with N applied only at the end of tillering at both locations in 1998–1999 and at Jemaa Riah in 2000–2001;

however, the lowest values were obtained with the same N treatment at Jemaa Shaim in 1999–2000 (Table X).

Table X. Effect of N combinations on grain and straw N uptake and on %N derived from fertilizer and nitrogen-use efficiency at Jemaa Riah and Jemaa Shaim, 1998–2002

Jemaa Riah Jemaa Shaim

Growing

season Parameter

0–40^a 40–0 40–46 0 0–40 40–0 40–46 0 Nup grain (kg/ha) 43.3a^b 38.9b 39.37b – 22.9a 17.6b 18.6b – Nup straw (kg/ha) 18.4b 19.6b 25.76a – 37.4a 22.5b 35.6a – Nup tot (kg/ha) 61.7a 58.5b 65.13a – 60.3a 40.1b 54.3a –

%NdffG 29b 22b 39a 43a 0.10b 41a

%NdffP 27b 25b 45a 60a 3.9b 55a

NUE grain (%) 26a 18b 18b 21a 0.03c 8.9b

NUE straw (%) 11 12 14 49a 2.3c 23b

1998–

1999

NUE tot (%) 37a 1b 32b 70a 2.3c 31b

Nup grain (kg/ha) 2.27 3.48 2.77 2.32 4.18 2.86 4.07 4.3 Nup st (kg/ha) 18.2 23.0 20.2 13.4 17.9b 25.1a 27.4a 16.8b Nup tot (kg/ha) 20.4 26.5 22.9 15.8 22.1b 27.9a 31.4a 21.1b

%Ndff grain 0 0 0 0 0 0

%Ndff straw 18b 19b 31a 4.9b 26a 24a

NUE straw (%) 7.2 11 7.1 2.0c 16a 7.4b

1999–

2000

NUE tot (%) 7.2 11 7.1 2.0c 16a 7.4b

Nup grain (kg/ha) 32.8a 32.1a 31.8a 25.3b 13.9ab 11.1b 10.4b 16.8a Nup straw (kg/ha) 27.6ab 26.8ab 30.7a 24.3b 28.8ab 33.0a 34.4a 23.6b

Nup tot 60.4a 58.9a 62.5a 49.5b 42.7ab 44.1a 44.8a 40.4b

%NdffG 13a 8.4b 5.9c 4.5b 4.1b 7.5a

%NdffP 12a 7.9b 5.1c 3.4b 3.4b 6.2a

NUE grain (%) 11a 6.8b 2.4c 1.8 1.3 1.0 NUE straw (%) 8.1a 5.2b 2.0c 2.4 2.7 2.6 2000–

2001

NUE tot (%) 19a 12b 4.3c 4.1 4.0 3.7

Nup grain (kg/ha) 14.6 15.0 15.2 15.9 71.9a 69.8a 80.6a 57.0b Nup straw (kg/ha) 12.7 13.9 13.5 12.4 24.7ab 22.5bc 29.7a 17.3c Nup tot (kg/ha) 27.3 28.9 28.8 28.3 96.5ab 92.3b 110a 74.4c

%NdffG 17b 15b 24a 19c 22b 31a

%NdffP 15b 13b 21a 14c 17b 23a

NUE grain (%) 6.4 5.9 4.6 32 37 31

NUE straw (%) 5.1 5.0 3.6 8.2 9.3 8.5

2001–

2002

NUE tot (%) 12 11 8.3 40 47 39

a Nitrogen treatments; see Materials and Methods.

b Numbers in a row within a location followed by different letters are significantly different (P<0.05).

3.3. Soil nitrate, percent nitrogen, organic matter and stability index

Applied N did not substantially increase soil nitrate, %OM or SI at Jemaa Riah in 1998–1999, 1999–

2000 or 2000–2001 (Table XI). However, at Jemaa Shaim, nitrate at sowing in the 0- to 20-cm layer [nitS(0–20)] increased with dual N application. The same results were obtained for nitrate at sowing in the 20- to 40-cm layer [nitS(20–40)] in 1999–2000 and for nitrate at harvest at 20 to 40 cm [nitH(0–20)] in 1998–1999.

Nitrogen losses probably occurred with the side-dressed N application that was followed by low rainfall and high temperature during most of the growing seasons.

Table XI. Effect of N on soil nitrate, OM, %N and stability index at sowing (S) and harvest (H) at Jemaa Riah and Jemaa Shaim, 1998–2002

Jemaa Riah Jemaa Shaim

Growing

season Parameter

0–46^a 40–0 40–46 0–0 0–46 40–0 40–46 0–0 NitS(0–20) (ppm) 23.7 26.8 24.5 28.3 28.8 42.1 27.0 29.8 1998–

1999 NitS(20–40) (ppm) 41.9 39.5 38.4 33.2 27.8 29.0 29.2 26.6 NitH(0–20) (ppm) 20.8 29.9 30.7 29.0 35.2 23.9 68.2 – NitH(20–40) (ppm) 29.7 25.2 28.0 41.9 22.9 20.4 19.9 – NitH(40–60) (ppm) 26.6 25.4 24.5 22.8 25.1 22.7 20.6 –

OM S (%) 1.3 1.4 1.2 1.4 1.4 1.4 1.5 1.4

OM H (%) 1.5 1.7 1.6 1.4 1.0 1.2 1.1 –

Nsol S (%) 0.15 0.15 0.19 0.17 0.07 0.08 0.07 0.09 Nsol H (%) 0.09 0.09 0.09 0.07 0.09 0.08 0.08 –

SI S 0.63 0.62 0.58 0.47 0.64 0.67 0.75 0.74

SI H 0.55 0.68 0.57 0.64 0.93 0.9 0.92 –

NitS(0–20) (ppm) 20.8 17.4 21.4 16.8 11.6 4.65 21.0 3.38 1999–

2000 NitS(20–40) (ppm) 18.0 9.89b 9.98 7.88 11.8 9.07 19.1 8.04

NitS(40–60) (ppm) – – – – 11.3 9.46 11.6 5.81

OMS (0–20) (%) 1.8 1.5 1.3 0.89 2.1 2.2 2.5 2.0 OM (20–40) (%) 1.4 1.7 1.6 1.3 2.1 1.6 0.93 1.5

Nit020 (ppm) 13.8 9.88 10.0 8.68 11.6 9.60 14.8 9.70 2001–

2002 OM (%) 1.6 1.47 1.37 1.27 1.58 1.08 1.34 1.44

a Nitrogen treatments; see Materials and Methods.

4. ECONOMICS

Both phases of each rotation were considered for each year. Vetch in W–VM was evaluated in terms of forage production and its revenue; incorporated vetch in W–VI required the same inputs without generating revenue. All expenses related to the various rotation phases, to fertilizer inputs and to management were accounted for (data not shown) along with revenues accrued to calculate the benefit:cost ratio.

The wheat–incorporated-vetch system had the lowest benefit:cost ratios at both locations in each of the four years (Table XII). The use of green manure in these semi-arid locations was not economically justified. Except for Jemaa Riah in the 2001–2001 season where W–VM had a better cost:benefit ratio, W–F had the highest cost/benefit ratios. The dry period of the experiment affected both wheat and, especially, vetch production.

Furthermore, soil-water conservation in W–F ensured grain production during the driest years when wheat in the other rotations failed to yield and vetch produced no dry matter. Despite these results, vetch alone or in a mixture with cereals, is still an alternative for continuous cropping in areas with more favorable rainfall and in shallow soils of low water-holding and/or storage capacities.

As discussed before, wheat responses to applied N were either negative or very low. Consequently, based on benefit:cost ratio, the application of N was not economically justified during the period of experiment (Table XIII) with three consecutive dry years.

Table XII. Benefit:cost ratios for rotations and years at Jemaa Riah and Jemaa Shaim

Jemaa Riah Jemaa Shaim

Growing

season W–F W–VM W–VI W–F W–VM W–VI

1998–1999 3.72 2.82 1.16 1.65 1.25 0.96 1999–2000 0.74 –0.24 –0.25 1.02 0.20 0.17 2000–2001 1.92 1.42 1.09 1.23 0.53 0.41 2001–2002 1.19 2.04 0.17 4.92 3.74 2.94

Table XIII. Benefit:cost ratios for various nitrogen combinations and years at Jemaa Riah and Jemaa Shaim

Jemaa Riah Jemaa Shaim

Growing

season 0–40^a 40–0 40–46 0 0–40 40–0 40–46 0–0

1998–1999 2.88 2.34 2.03 3.32 1.41 1.23 0.91 1.78

1999–2000 0.09 0.06 –0.12 0.17 0.51 0.36 0.24 0.70

2000–2001 1.72 1.37 1.22 1.75 0.85 0.57 0.42 1.13

2001–2002 1.32 1.06 0.91 1.66 4.24 3.71 3.33 4.56

aNitrogen treatments; see Materials and Methods.

5. CONCLUSION

The three consecutive dry years affected grain yields, even in the wheat–fallow system, at both locations. Fallowing ensured grain production in both locations, where the wheat–vetch system failed to produce grain in the driest year. Rainfall distribution affected wheat yield more did than total precipitation. Consequently N either depressed or did not affect yield in the different cropping systems. Nitrogen-use efficiency was in general highest with wheat fallow at both locations. The severe drought, coupled with bad rain distribution resulted in no yield response to N and in low NUE values. There was no difference among rotations in terms of soil %OM and only a small difference with respect to soil nitrate. This was due to low green manure production, which was nil in the driest years. Nitrogen did not affect soil water in the different profiles and rotations. Incorporated vetch is not economically justified in this semi-arid region, where water is the main limiting factor for crop production. As a forage, vetch is still a viable alternative to continuous wheat.

REFERENCES

[1] WATTS, G., EL MOURID, M, Rainfall Patterns and Probabilities in the Semi-Arid Cereal Production Region of Morocco, INRA Centre Aridoculture, Settat (1988).

[2] STANHILL, G., Water use efficiency, Adv. Agron. 39 (1986) 53–85.

[3] BOUZZA, A., Water Conservation in Wheat Rotations under Several Management and Tillage Systems in Semi-Arid Areas, PhD Thesis, University of Nebraska, Lincoln (1990).

[4] EL MEJAHED, K., Effect of N on Yield, N Uptake and Water Use Efficiency of Wheat in Rotation Systems Under Semi-arid Conditions of Morocco, PhD Thesis, University of Nebraska, Lincoln (1993).

[5] KACEMI, M., Water Conservation, Crop Rotations, and Tillage Systems in Semi-arid Morocco, PhD Thesis, Colorado State University, Fort Collins (1992).

[6] MAZHAR, M., Effect of Crop Rotation on Wheat and Herbage Yield, Evapotranspiration and Water Use Efficiency in Morocco, PhD Thesis, University of Missouri, Columbia (1987).

[7] AMIR, J., et al., Wheat production in an arid environment. 1. Water use efficiency, as affected by management practices, Field Crops Res. 27 (1991) 351–364.

[8] AMIR, J., et al., Wheat production. 2. Role of soil pathogens, Field Crops Res. 27 (1991) 365–

367.

[9] EL GHAROUS, M., et al., Nitrogen mineralization potential of arid and semi-arid soils of Morocco. Soil Sci. Soc. Am. J. 54 (1990) 438–443.

[10] HALVORSON, A.D., REULE, A.C., Nitrogen fertilizer requirements in an annual dryland cropping system, Agron. J. 86 (1994) 315–318.

[11] HALVORSON, A.D., REULE, A.C., Nitrogen fertilizer effects on dryland crop yield, water use, and soil nitrogen, Great Plains Agric. Council Bulletin 150 (1994) 43–50.

[12] KOLBERG, R. L., et al., Cropping intensity and nitrogen management impact of dryland no-till rotations in the semi-arid western Great Plains, J. Prod. Agric. 9 (1996) 517–522.

[13] MRABET, R. Crop Residue Management and Tillage Systems for Water Conservation in a Semi-Arid Area of Morocco, PhD Thesis, Colorado State university, Fort Collins (1997).

[14] ROMMAN, L., “Légumineuses fourragères de saison froide”, Rapport d’Activité 1984–85.

Centre Aridoculture, Setta (1985) 79.

[15] TIEDMAN, J., et al., “Comparaison des rotations jachère en herbe/céréale et Medicago/céréale”, Rapport d’Activité 1991–92, Centre Aridoculture, Settat (1992).

[16] SCHROEDER, J.L., et al., Utilization of cowpea crop residues to reduce fertilizer nitrogen inputs with fall broccoli, Crop Sci. 38 (1998) 741–749.

[17] WARMAN, P.R., “Principe fondamentaux de la culture d’engrais vert”, Ecological Agriculture Projects, McGill University, Montreal (1981).

[18] MILLETTE, P., 1993. Rotations des Cultures et Engrais Verts, Institut de Technologie Agro-Alimentaire, La Pocatière (1993).

[19] ZOHARY, D. HOPF, M., Domestication of Plants in the Old World, Clarendon, Oxford (1988).

[20] ERSKINE, W., et al., Mimicry of lentil and the domestication of common vetch and grass pea, Economic Botany 48 (1994) 326–332.

[21] PAUL, W., et al., Cover crop effects on soils water relationships, J. Soil Water Conservation 53 (1998) 200–206.

[22] WALLEY, F.L., et al., Water-use efficiency and carbon isotope composition in reduced tillage systems, Soil Sci. Soc. Am. J. 63 (1999) 356–361.

[23] FARQUHAR, G.D., et al., On the relationship between carbon isotope discrimination and the intercellular carbon dioxide concentrations in leaves, Aust. J. Plant Physiol. 9 (1982) 121–137.

[24] CONDON, A.G., et al., Carbon isotope discrimination is positively correlated with grain yield and dry matter production in field-grown wheat, Crop Sci. 27 (1987) 996–1001.

[25] CONDON, A.G., et al., Relationship between Carbon isotope discrimination, water use efficiency and transpiration efficiency for dryland wheat, Aust. J. Agric. Res. 44 (1993) 1693–1711.

[26] SIMONIS, A.D., “Studies on nitrogen use efficiency in cereals”, Nitrogen Efficiency in Agricultural Soils (JENKINSON, D.S., SMITH, K.S., Eds.), Elsevier Applied Science, Amsterdam (1988) 110–124.

[27] BLOOM, T.M., et al., 1988. “Apparent recovery of fertilizer nitrogen by winter wheat”, Nitrogen Efficiency in Agricultural Soils (JENKINSON, D.S., SMITH, K.S., Eds.), Elsevier Applied Science, Amsterdam (1988) 27–45.

[28] NIELSON, N.E., et al., “Efficiency of fertilizer nitrogen uptake by spring barley”, Nitrogen Efficiency in Agricultural Soils (JENKINSON, D.S., SMITH, K.S., Eds.), Elsevier Applied Science, Amsterdam (1988) 67–71.

[29] McVAY, K.A., et al., Winter legume effects on soil properties and nitrogen fertilizer requirements, Soil Sci. Soc. Am. J. 53 (1989) 1856–1862.

[30] JOFFE, J.S., Green manuring viewed by a pedologist. Adv. Agron. 7 (1955) 141–187.

[31] FRYE, W.W., et al., “Role of annual legume cover crops in efficiency use of water and nitrogen”, Cropping Strategies for Efficient Use of Water and Nitrogen, ASA special Publication 51 (HARGROVE, W.L., Ed.), Am. Soc. Agron., Madison (1988) 129–154.

[31] ZENTER, R.P., et al., Indian head black lentil as green manure for wheat rotations in the brown soil zone, Can. J. Plant Sci. 76 (1996) 417–422.

[32] ALLISON, J.R., OTT, S.L., “Economics of using legumes as a nitrogen source in conservation tillage systems”, The Role of Legumes in Conservation Tillage Systems (POWER, J.F., Ed.), Soil and Water Conservation Society of America, Ankeny (1987) 145–149.

[33] MacRAE, R.J., MEHUYS, C.R., The effect of green manuring on the physical properties of temperate-area soils, Adv. Soil Sci. 3 (1985) 71–90.

[34] MANN, H. H., Field studies in green manuring, Emp. J. Exp. Agric. 27 (1959) 243–251.

[35] DE HANN, S., “Humus, its formation, its relation with the material part of the soil and its significance for soil productivity” Soil Organic Matter Studies Vol. II, International Atomic Energy Agency, Vienna (1977) 21–30.

[36] SOWDEN, F.J., ATKINSON, A.J., Effect of long-term annual addition of various organic amendments on the nitrogenous components of a clay and sand, Can. J. Soil Sci. 48 (1968) 331–339.

[37] RUSSEL, E.W., Soil Condition and Plant Growth, Tenth Edition, Longman’s, New York (1973).

[38] KARROU, M., “Mécanismes d’adaptation du blé aux stress hydrique et azote”, Rapport d’Activité 1991–92, Centre Aridoculture, Settat (1992) 80.

[39] EL HERZENNI, A., “Utilisation des engrais par les agriculteurs de la chaouia et abda”, Proc.

Third Seminar on Soil Fertilization, ENA, Meknés (1988) 6–9.

APPENDIX

A1. JEMAA RIAH SOIL PROFILE Ap: 0–13 cm:

dark reddish brown (5YR 3/3), clay loam; week subangular blocky and granular structure; firm.

A1: 13–28 cm: Dark reddish brown (5YR 3/3), clay loam; week, very coarse prismatic structure, massive to granular inside, very firm, many worm casts; many roots

Bu: 28–65 cm: Reddish brown (2.5 YR 4/4), clay; moderate, very coarse prismatic structure, parting to moderate medium and coarse angular blocky; pressure faces, wedge-shaped aggregates and parallelepipeds; dense; roots between pods.

Bk: 65–100 cm: Red (2.5 YR 4/6) clay loam; week very coarse prismatic and medium subangular blocky structure; firm; common to many carbonate accumulation, few with hard centres.

A1.1. Diagnostic features 1- Ochric epipedon 2. Calcic horizon (k) 3. Gilgai

4. Slickensides, wedge-shaped aggregates, cracks 5. Xeric moisture regime

6. Thermic temperature regime

The soil was classified as a fine montmorillonitic, thermic Palexerollic chromoxeret Soil capability subclass: Iie

A.2. JEMAA SHAIM SOIL PROFILE

Dans le document Nutrient and Water Management Practices for Increasing Crop Production in Rainfed Arid/Semi-Arid Areas | IAEA (Page 106-112)