RESPONSE OF WINTER WHEAT TO CHLORIDE FERTILIZATION IN SANDY LOAM SOIL 

K. W. Freeman¹, K. Girma¹, J. Mosali², R. K. Teal¹, K. L. Martin¹ and  W. R. Raun^1*

¹Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078
² The Samuel Roberts Noble Foundation, Inc., 2510 Sam Noble Parkway, Ardmore, OK 73401

Contribution from the Oklahoma Agricultural Experiment Station

* Correspondence: William R. Raun, 044 North Ag Hall, Department of Plant and Soil Sciences, Oklahoma State University, OK 74078; Fax: (405) 774 5269; E-mail: wrr@mail.pss.okstate.edu.

ABSTRACT

Chloride (Cl) as a yield and growth limiting nutrient has been the object of experimental attention for the last several decades. Long-term experiments were conducted from 1996 to 2002 at Hennessey and Perkins, Oklahoma to evaluate the response of winter wheat grain yield and N uptake to 0, 15 and 30 kg Cl ha^-1 rates. A randomized complete block experimental design with three replications was used at both sites. Grain yield data were subjected to statistical analysis using SAS. Polynomial Orthogonal contrasts were used to detect trends in grain yield and N uptake to chloride levels. Chloride fertilizer significantly increased wheat grain yields in 50% of the site-year combinations (14 site years), and the increases were more notable on the sandy loam soil included in this study.

 

INTRODUCTION 

Chloride is an essential plant nutrient involved in several processes taking place in the plant including osmotic regulation (1), photosynthesis by evolution of O₂ in photosystem, enzyme activation, and transportation of other plant nutrients (2, 3, 4), plant development, lodging prevention and disease suppression (5, 6). Chloride has also been found to control physiological leaf spotting in some winter and durum wheat varieties and barley (7, 8).

As a yield and growth limiting nutrient, chloride has been the object of experimental attention for the last several decades. However recent publications related to chloride nutrition contained contradicting reports where some reported the importance of supplementing crops with this nutrient while others not. The latter conclusion esteemed from the fact that chloride is required by plants in a very small amount and this amount can be obtained from the processes in the soil and the surrounding environments plus from fertilizers designed to supply crops with macro-nutrients such as K and Ca (eg. KCl and CaCl₂) (9). These compounds contain some chloride in them that can be used by crops to satisfy their requirement. Annual chloride depositions of 13 to 40 kg ha^-1 in precipitation are common and may increase to more than 112 kg ha^-1 in coastal areas.  Due to the distance away from seawater high in Cl, inland areas are known to receive much lower amounts of Cl in rainfall.  Several of the current chloride related research activities are focused on the benefits obtained from chloride in suppressing foliar and root diseases (10, 11, 12, 13) than grain yield.

 

However, there are several research works continued on demonstrating the importance of fertilizing crops with chloride in USA and else where to maintain grain yields specially in soils where the soil chloride is low such as sandy and sandy loam soils (14).  According to Grant et.al. (15) soil chloride level less than 36 kg ha^-1 in the top 0.6 m of soil is generally used as an indication of insufficient quantity and a level between 36-72 kg ha^-1 is assumed to be adequate.  Chloride response to yield follows the concept of response of crops to mobile nutrients. This means, the yield can be related directly to the amount of chloride given this nutrient is the most limiting one in the soil. It is also important to note that chloride is mobile and subject to leaching.  Argentina research conducted on coarse textured Mollisols showed that, chloride fertilization increased wheat grain yields in 50% of the sites. Averaged over 10 locations, the grain yield benefit due to chloride fertilization was 253 kg ha ^-1 and it was mostly explained by a greater number of grains per square meter (16).  Soil chloride levels of 13.2 mg kg^-1 were adequate for maximum grain yields (16).  Research conducted in Canada between 1996 and 1998 on clay loam and fine sandy loam textured soils revealed that soil chloride levels were low in all years at the fine sandy loam site and in 1996 and 1998 at the clay loam site (17).  Research in the Great Plains (showed  that chloride significantly increased wheat grain yields by as high as 1546 kg ha^-1 at three sites increasing gross return by 50 $ ha^-1 (18).  Generally, wheat grown in chloride deficient soils responded positively to chloride rates less than 50 kg ha^-1.  Research findings suggest that soil (0-25 cm) chloride levels less than 33 kg ha^-1, will require 22 kg Cl ha^-1 applied as KCl (19).  Further, the concentration of chloride in wheat should be 0.4 percent in the whole plant at the boot to flowering stage to achieve maximum yield potential (20).  Research conducted in the Great Plains of the USA showed that yield response occurs about half the time when plant chloride is between 0.12 and 0.4 percent, but it occurs 80 percent of the time when plant chloride concentrations are 0.12 percent or less (20). Similar results were also reported from research conducted in the Pacific Northwest regions of the USA where chloride fertilization practices increased productivity of wheat and other crops (4, 21).

 

One of the important functions of chloride as a whole is its significance in suppressing some foliar diseases. In this respect several research findings were published (10, 11, 22). All these findings documented the benefits of chloride fertilization in lowering the negative effects of disease during the development of the crops and the subsequent improvement in yield.  In Texas, topdress applications of chloride have caused significant reduction of leaf rust and septoria ratings at bloom, and significant yield responses. They found a strong positive and significant interaction between chloride and systemic foliar fungicides which are commonly used in wheat (10). 

 

Some researchers attribute the chloride effect to non-disease wheat growth limiting factors (6, 23). According to these researchers chloride fertilization is beneficial in preventing the occurrence of a leaf spot syndrome that is not disease related (21, 24). In support to their argument they suggested that 48 kg ha^-1 chloride fertilization decreased physiological leafspot on winter wheat in Saskatchewan.

 

Others claim that chloride may increase wheat grain yields by enhancing NH₄⁺ supply attributed to lower leaf osmotic potentials, delayed nitrification in the soil, and inhibition of take-all root rot (Gaeumannomyces graminis) disease (12, 25). This is an interesting aspect of chloride since this indicates that the uptake of major nutrients like N depends on its availability in the soil. In fact several researchers underlined chlorides role in uptake of other nutrients especially macro-nutrients such as nitrogen.

 

In Oklahoma, research conducted for eight years chloride on wheat grain yield and take-all disease it was found that only in two years yield was significantly affected by chloride levels (13). This was apparently because of the high chloride level in the soil of the experimental site which was a silty loam. Soil survey research across the state however, revealed that about 32% of  soil samples collected from 17 counties had chloride less than optimum for soil samples 60 cm deep (26). This means that the top soil where wheat roots are abundant, the nutrient is below optimum level. According to this report, in the surface soil (15 cm), 98% of the samples showed response to chloride fertilization. Another two year and three site data in Oklahoma showed an inconsistent response of wheat grain yield to applied chloride (27).

 

In todays wheat production in Oklahoma farmers use mainly nitrogen and phosphorus fertilizers which do not have chloride. The practice of avoiding fertilizers containing metallic salts of chloride shows possible deficiency of chloride in soils for crop requirement especially in high yielding deep sandy soils with low organic matter (28). According to the National Atmospheric Deposition Program (NADP), chloride deposition is decreasing by 0.04 kg ha^-1 annually since 1983 (29) due to various measures to reduce pollution. This indicates that chloride as a micro-nutrient needs to be studied for cropping systems and soil conditions of a given agro-ecology. Additionally, few studies were made to assess the effect of chloride on uptake of N by wheat. With this in mind, long-term chloride experiments were initiated in 1995 at two locations in different soils in Oklahoma to assess the response of winter wheat grain yield and N uptake to chloride fertilizer.

 

MATERIALS AND METHODS

Two experiments were conducted from 1996 to 2002 at Hennessey (Shellabarger sandy loam- fine-loamy, mixed, thermic Udic Argiustolls) and Perkins (Teller sandy loam -fine-loamy, mixed, thermic Udic Argiustolls), Oklahoma to evaluate the response of winter wheat grain yield and N uptake to chloride fertilizer. The Hennessey location is a typical environment for wheat production in North Central Oklahoma. The Perkins location is on a deep, sandy, low organic matter soil which is more prone to leaching of mobile nutrients including chloride in soil solution. Initial soil test data are reported in Table 1. A one to one soil to water paste was used to extract initial soil chloride (30) and was quantified using a Lachat (Milwaukee, WI) flow injection analyzer.

 

A randomized complete block experimental design with three replications was used at both sites with three rates of 0, 15 and 30 kg Cl ha^-1 using calcium chloride (CaCl₂).  Plot sizes were 4.9 m by 6.1 m.

The winter wheat variety Tonkawa was used during the 1996 to 1999 cropping seasons. This variety was replaced by Custer from 2000 to 2002. Wheat was planted between October and November for all experiments at a seeding rate of 98 kg ha^-1. All other crop management practices were carried out as per the recommendation of the respective sites. Wheat was harvested from the center of each plot in June with a Massey Ferguson 8XP plot combine, removing an area of 2.0 m by 6.1 m.  A Harvest Master yield-monitoring computer installed on the combine recorded yield data and sub-samples were collected. Grain samples were dried in a forced-air oven at 66^oC, ground to pass a 140 mesh sieve (100 μm), and analyzed for total N content using a Carlo-Erba 1500 dry combustion analyzer.

 

Grain yield data were subjected to statistical analysis using SAS (31). Polynomial orthogonal contrasts were used to detect trends in grain yield or N uptake in response to chloride levels.

 

 

RESULTS AND DISCUSSION

Grain Yield

 

Chloride rates significantly increased wheat grain yield in 50% of the year-site combinations (Tables 2 and 3). At Hennessey in 1998 a quadratic trend was observed. The response at Hennessey in 1998 showed a common response trend of mobile nutrients such as chloride. In 2001, wheat grain yield increased linearly with an increase in chloride levels.  Even though not significant, an increasing linear trend in grain yield was observed at Hennessey in 1997 as well as in 2002. In contrast, in 2000 a decrease in yield was observed with an increase in chloride rate. The average increment in grain yield (cf. no chloride check) averaged over years was only 2 and 4%, respectively for 33.6 and 67.2 kg ha^-1 chloride rates. The increase in grain yield for some of the years might be attributed to nitrification inhibition in soils where pH was low as reported by previous research (12, 32). The conditions that induce chloride response of crops in soils such as Hennessey are primarily rainfall and pH. The initial soil chloride levels both on the surface 0-15 cm and depth of 0-60 cm (Table 1) were slightly lower than that required for optimum yield. This explains the irregularity in response observed at this location.

 

At Perkins wheat grain yield was significantly influenced in four years in 1996, 1997, 1999 and 2000 and the average of all years. In all cases, a linear response was observed where yield was increased with an increase in chloride rate. Over years, 33.6 and 67.2 kg ha^-1 chloride fertilization resulted in 5.0 and 14.5% increment in grain yield. The fact that this site is characterized by a sandy loam soil might explain the linear response to chloride. The initial soil test level of 6.0 mg kg^-1 at this site was way below the 13.2 mg kg^-1 required for optimum grain yield when chloride is the most limiting nutrient. This partially explains why significant responses to chloride were obtained at Perkins. As an anion, chloride is not readily adsorbed on the soil exchange complex or organic matter and mostly present in the soil solution. Because of this, chloride moves readily with soil water and is more prone to loss in sandy soils. This results in a quick depletion of chloride deposited in the soil resulting in deficiency and subsequent response of wheat to applied chloride.

 

The results from this site clearly shows that sandy loam soils in Oklahoma need to be supplemented with chloride especially if potassium is inherently available and if calcium is not applied to the soils since the fertilizer form of these two nutrients contain chloride. This is an important part of wheat management as farmers tend to supply wheat mainly with nitrogen and phosphorus fertilizers and not potassium leading to chloride deficiency in those soils. The results obtained here are also in agreement with previous research reports (13, 25, 26).

 

Grain N Uptake

 

Chloride levels affected this variable in two of seven years at Hennessey, in one of seven years at Perkins (Table 4 and 5) and the average of years at both locations. In 2001 at Hennessey and 2000 at Perkins a significant linear response in grain N uptake was obtained with increasing rates of chloride while a quadratic response was obtained at Hennessy in 1998. In 1996 and 1999 at Hennessey the N uptake decreased linearly with increasing chloride rates even though not significant where as it was increased linearly in 1998 and 1999 at Perkins. Although significant differences in N uptake due to chloride fertilization were found only in three of the 14 experiments, seven experiments showed a linear increase, five of them showed an increasing and then a decreasing quadratic response. Overall, application of 33.6 and 67,2 kg ha^-1 chloride at Hennessey site resulted in 3.5 and 5.6% grain N uptake, respectively compared with the no chloride check. At Perkins the two chloride rates resulted in 7.5 and 14.8% increase in grain N uptake. This suggests that chloride has a direct or indirect effect on N uptake by wheat crop. This could be due to an antagonistic effect of chloride on NO₃^- in the leaf tissue which might have affected N uptake in grain as reported by previous research (12). The physiological basis of this response however, needs to be further studied.

REFERENCES 

1. Kafkafi, U.; Xu, G. Chlorine. In Encyclopedia of soil science; Lal, R., ed. Marcel Dekker: New York, 2002; 152 155.

2. Broyer, T.C.; Carlton, A.B.; Johnson, A.B.; Stout, P. R. Chlorine: A micronutrient element for higher plants. Plant Physiol. 1954, 29, 526 to 532

3. Ozanne, P.G.; Woolley, J.T.; Broyer, T.C.. Chlorine and bromine in the nutrition of higher plants. Austr. J. Biol. Sci. 1957, 10, 66 to 79.

4. Grant, C.A.; Lamond, R.; Mohr, R.M. Chloride research: What have we learned? 2003 ASA, CSSA, SSSA annual meetings abstracts [CD-ROM]. ASA, CSSA, and SSSA: Madison, WI, 2003.

5. Wallace, T. The Diagnosis of Mineral Deficiencies in Plants by Visual symptoms. Her Majesty's Stationary Office: London, 1944; 116 pp.

6. Engel, R.E.; Ecknoff, J.; Berg, R.K. Grain yield, kernel weight, and disease responses of winter wheat cultivars to chloride fertilization. Agron. J. 1994, 86, 891 to 986.

7. Smiley, R.W.; Gillespie-Sasse, L.M.; Uddin, W.; Collins, H.P.; Stoltz, M.A.  

Physiologic leaf spot of winter wheat. Plant Dis. 1993, 77, 521 to 527.

8. Engel, R. E.; Bruebaker, L.; Emborg, T. J. A Chloride deficient leaf spot of durum wheat.  Soil Sci. Soc. Am. J. 2001, 65 (5), 1448 to 1454.

9. Carr, P.M.; Martin, G.B.; Melchior, B.A. Spring wheat response to chloride applications in southwestern North Dakota. Agronomy Section 2001 Annual Report Dickinson Research and Extension Center: Dickinson, ND, 2001.

10. Miller, T.; Jungman, M. Chloride fertilizer in winter wheat - effect of Cl and interactions with foliar fungicides under severe leaf rust pressure. Proceedings of Intensive Wheat Management Conference , March 4 to 5, 1998; Texas Agricultural extension Service, The Texas A&M University System: College Station, TX, 1998.

11. Engel, R.E.; Grey, W.E. Chloride fertilizer effects on winter wheat inoculated with Fusarium culmorum. Agron. J. 1991, 83, 204 to 208.

12. Christensen, N.W.; Brett, M. Chloride and liming effects on soil nitrogen form and take-all of wheat. Agron. J. 1985, 77, 157 to 163.

13. Thomason, W.E.; Wynn, K.J.; Freeman, K.W.; Lukina, E.V.; Mullen, R.W.; Johnson, G.V.; Westerman, R.L.; Raun, W.R. Effect of chloride fertilizers and lime on wheat grain yield and take-all disease. J. Plant Nutr. 2001, 24 (4&5), 683 to 692.

14. Sillanp, M. Micronutrients and the nutrient status of the soils: A global study. FAO: Rome, 1982.

15. Grant, C. A.; McLaren, D.L.; Johnston, A.M. Spring wheat cultivar response to potassium chloride fertilization. Better Crops 2001, 85 (4), 20 to 23.

16. Diaz Zorita, M; Duarte, G. A.; Barraco, M. Effects of chloride fertilization on wheat (Triticum aestivum L.) productivity in the sandy Pampas region, Argentina. Agron. J. 2004, 96 (3), 839 to 844.

17. Roberts, T. L. Chloride: Can we close the book? The Potash & Phosphate Institute (PPI) and the Potash & Phosphate Institute of Canada (PPIC): Saskatoon, Saskatchewan Canada 1999.

18. Lamond, R.E.;  Roberson, D. D.; Rector, K. Chloride fertilization bumps wheat yields, profits.  Fluid J. 1999 Issue 27, Vol. 7, No. 4, 14 to 15.

19. Lamond, R. E.; Leikam, D. F. Chloride in Kansas: Plant, Soil, and Fertilizer Considerations. Kansas State University, Kansas State University Agricultural Experiment Station and Cooperative Extension Service: Manhattan, KS, 2002; MF2570.

20. Lamond, R. How do we manage chloride? In 2003 ASA CSSA SSSA annual meetings abstracts. ASA CSSA SSSA, Madison, WI, 2003.

21. Engel, R.E.;  Bruckner, P.L.;  Mathre, D.E.;  Brumfield, S.K.Z. A chloride-deficient leaf spot syndrome of wheat. Soil Sci. Soc. Am. J. 1997, 61, 176 184.

22. Christensen, N.W.; Taylor, R.G.; Jackson, T.L.; Mitchell, B.L. Chloride effects on water potentials and yield of winter wheat infected with take-all root rot. Agron. J. 1981 73, 1053 to 1058.

23. Fixen, P.E. Crop responses to chloride. Adv. Agron. 1993, 50, 107 to 150.

24. Smiley, R.W.; Uddin,W.; Zwer, P.K.; Wysocki, D.J.; Ball, D.A.; Chastain, T.G. Influence of crop management practice on physiologic leaf spot of winter wheat. Plant Dis. 1993, 77, 803 to 810.

25. Koening, R.T.; Pan, W.L. Chloride enhancement of wheat responses to ammonium nutrition. Soil Sci. Soc. Am. J. 1996, 60, 468 to 505.

26. Zhang, H. Soil chloride, nitrate and sulfate in Oklahoma soils. Soil Fertility Research Highlights, Oklahoma State University: Stillwater, OK, 2000; 329 to 331. 

27. Zhang, H.; Raun, W.R. Soil chloride and sulfate status in Oklahoma soils. Proceedings of the Southern Plant Nutrient Management Conference, October 5-6, 2004, Olive Branch, MS; Crozier, C., ed.; The Samuel Roberts Noble Foundation: Ardmore, OK, 2004; 97 to 100.

28. LaRuffa, J.M.; Johnson, G.V.; Phillips, S.B.; Raun,W.R. Sulfur and Chloride Response in Oklahoma Winter Wheat. Better Crops 1999, 32 (4), 28 to 30.

29. National Atmospheric Deposition Program (NADP). National Atmospheric Deposition Program 2002 Annual Summary. NADP Data Report 2003. NADP Program Office: Champaign, IL, 2003. 16 pp.

30. Diamond, D. Determination of Chloride by Flow Injection Analysis Colorimetry. QuikChem Method 10 117 07 1 B. Lachat Instruments: Milwaukee, WI, 1994.

31. SAS Institute. The SAS system for windows, Version 8.02; SAS Institute: Cary, NC, 2001.

32. Roseberg, R.J.; Christensen, N.W.; Jackson, T.L. Chloride, soil solution osmotic potential, and soil pH effects on nitrification. Soil Sci. Soc. Am. J. 1986 50, 941 945.