Janzen, H.H.

Lindwall, C.W.

Roberts, T.L.

English

eCommons@USASK

Fertilizer-use efficiency of point injected N in winter wheat

University of Saskatchewan Research Archive

Fertilizer-Use Efficiency of Point Injected N in Winter Wheat T. L. Robertsl, H. H. Janzen2 and C. W. Lindwall2 Introduction Nitrogen fertilizer can be applied to winter wheat in the fall prior to seeding or as a topdress in the spring. In the former practise, fertilizer is subject to overwinter loss from leaching, denitrification and volatilization, and has been shown to be recovered less efficiently than spring applications (Christensen and Meints 1982, Grant et al. 1985, Fowler 1982). Furthermore, high rates of N application in the fall tend to increase susceptibility to root rot and winter damage (Grant et al. 1984, Tyler et al. 1981). Spring-applied N can also be used inefficiently because of ammonia volatilization (Keller and Mengel, 1986), N immobilization in surl'ace residues (Sharpe et al. 1988) or "stranding" in a dry surl'ace soil layer (Harapiak et aL 1986). Point injection may improve the fertilizer-use efficiency over that of conventional methods for N application in winter wheat. Because it places fertilizer directly into the rooting zone with minimal soil disturbance, point injection facilitates effective N placement after crop establishment, thereby providing considerable flexibility in time of application. Recent small plot studies utilizing 15N labelled fertilizers ha,ve shown that point injection can result in higher fertilizer-use efficiency compared to broadcast methods (Janzen et al. 1990) and that fertilizer-use efficiency tends to be greatest when applied in N is applied in early spring (Janzen unpublished data). The objective of this work is determine the influence of time, method and rate of N application on N fertilizer use efficiency in winter wheat This paper presents preliminary data from the first year of the study. Materials and Methods A field study was conducted at three locations in southern Alberta at Cranford (Brown Chemozem), Lethbridge (Dark Brown Chemozem) and Pincher Creek (Black Chemozem) during the 1988/1989 growing season. Soil samples (0-60 em) taken in the fall of 1988 showed the Cranford, Lethbridge and Pincher Creek sites contained 22,54, and 29 kg ha-l of available N (N03-N and Nl4-N), respectively. The experimental design included four application times (seeding, late fall, early spring, and late spring), four N rates (20, 40, 60 and 80 kg ha-l) and two application methods (broadcast ammonium nitrate [BC] and point-injected urea-ammonium nitrate 1 Potash & Phosphate Institute of Canada. Coaldale, Alberta 2 Agriculture Canada, Lethbridge, Alberta 26 solution [PI]). In addition, a bandeg urea treatment was included at seeding and two controls giving a total of 38 treatments per site. The treatments were arranged in a randomized complete block design With either four (plot size, 3 m X 20 m) or six (plot size, 3 m X 15 m) replicates . Winter wheat (Triticum aestiyum 'Norstar') was seeded no-till into stubble. Growing season precipitation (April, May, June and July) was below normal at Lethbridge (174 vrs 199 mm) and above normal at Cranfoni"(196 vrs 182 mm) and Pincher Creek (279 vrs 192 mm). The plots were harvested with a small plot combine and yields have been reported on a moisture-free basis. Results and Discussion Yields Nitrogen fertilization did not result in a yield response at the Lethbridge site due to high residual soil N and lower than normal growing season precipitation. However, significant yield increases did occur at the Cranford and Pincher Creek sites. Treatment effect, however, varied between sites. Yields were significantly influenced by time (P-=0.01) and rate of N application (P=0.0001) at Cranford, and by method (P=0.07) and rate (P=0.001) at Pincher Creek. However, since the interactive effects of time, method and rate were not significant at either site, only the main effects are presented here. At Cranford, highest grain yields were observed when N was applied in early spring, although yields were only marginally higher than the seeding application (Table 1 ). Straw showed a similar response, but in this case yields were higher for the seeding application followed by the early spring. Lowest yields occurred when N was applied in late spring. Yields increased linearly with N rate (r2 = 0.949 and 0.936 for grain and straw, respectively) with maximum yields occurred at the 80 kg/ha rate. Table 1. Effect of time and rate of N application on winter wheat yields at Cranford in 198811989. Time Seeding Late Fall Early Spring Late Spring Rate (kg N/ha) 0 20 40 60 80 Grain yield Ck~a> 2364 2194 2398 2150 1849 1934 2246 2397 2464 27 Straw yield Ck&Jbal 2671 2545 2637 2150 2081 2134 2476 2627 2698 -= -= -~ ~ --= -~ ·;.. = ·; .. ~ At Pincher Creek, highest yields were observed in the PI treatments and like those at Cranford, yields increased in a linear fashion (r2 = 0.964 and 0.965, respectively) with maximum yields occurring at the 80 kg N/ha rate (Table 2). However, the response to applied N was not as great. Maximum increases in grain yield at Pincher Creek were 21% compared to 33% at Cranford. Table 2. Effect of method and rate of N application on winter wheat yields and N uptake in Fincher Creek in 198811989. Grain yield Straw yield Total N uptake <k~a) <kWh a) <kWh a) Method Broadcast 3995 6393 98.9 Point Injection 4163 6662 104.2 Rate (kg N/ha) 0 3557 5691 78.7 20 3846 6154 90.9 40 3926 6281 92.8 60 4226 6762 107.3 80 4312 6899 114.4 Inclusion of banding treatments at time of seeding did not improve grain yields over the other application methods (Fig.1). Contrast analysis showed yield response to BC and PI applications to be higher than that from banding at Cranford (P=0.03 and 0.001, respectively) and at Pincher Creek (P = 0.06 and 0.02, respectively). Broadcast and PI applications at either site were not significantly different from each other. The poorer pexformance of the banding treatments relative to the others may be attributed to drier soil conditions. The banding operation, carried out prior to seeding, caused greater soil disturbance and possibly greater loss of moisture from the surface soil than that of either the BC or PI treatments. Cranford Pincher Creek 2800 5000 2600 4500 2400 2200 4000 2000 3500 1800 1600 3000 20 40 60 80 20 40 60 80 N Rate (kg/ha) N rate (kg/ha) Figure 1. Influence of method of application at seeding on grain yields at Cranford and Fincher Creek in 1988/1989. 28 N Concentration and Uptake Nitrogen concentrations in grain and straw at Pincher Creek were not affected by time or method of application, bufintreased significantly (P = 0.0001) with N rate (Table 3). Concentrations in grain ranged from 1.65 to 1.92 %, which corresponds to a crude protein (%N X 6.25) concentration of 10.3 to 12.0 %. In Alberta, crude protein of fall wheat typically ranges between 9.6 and 17.9% with a mean of 13.7% (Alberta Agriculture 1987). The high yields at this site arising from favorable moisture conditions would have contributed to the generally lower N contents by a dilution effect Table 3. Influence of rate of N application on N concentration in m,in and straw at Pincher Creek in 1988/1989. N Rate (kglha) 0 20 40 60 80 ----------------------- % N -----------------------grain Straw 1.65 1.72 1.73 1.83 1.92 0.36 0.39 0.39 0,44 0.45 Removal of N by the crop was influenced by method and rate of application but not time of application, nor their interaction. When averaged across time and rate, uptake of N tended to be higher in PI treatments than in BC treatments (Table 2). However, differences were relatively small, but were statistically significant (P = 0.108). Like yields and N concentrations, total N uptake increased linearly with increasing N rate. The 80 kg N/ha treatments removed 45% more N than the unfertilized control. Grain N uptake averaged 72% of the N removed by the crop and was significantly influenced by method (P = 0.10) and rate of application (P = 0.0001). A significant interaction between time and method was also observed at the 10% probability level. Uptake generally increased with rate regardless of time of application, but differences in uptake between methods were inconsistant (Fig. 2). At seeding BC applications tended to result in greater N uptake in grain than PI, while the opposite occurred when N was applied in early spring. Surprisingly, the highest uptake occurred at the 80 kg N/ha rate with PI in the late spring application. At this rate, grain uptake in the PI treatments were 28% higher than that in the BC treatments. Discussion After one year of data, the influences of time, method and rate of application on winter wheat yields were inconsistent among the three sites studied. Wheat at Lethbridge did not respond to applied N, while the response at Cranford and Pincher Creek varied. 29 -= .c -~ ..:.:: -c ·; a.. ~ .5 ~ ..:.:: = -c. = z Application of N at seeding or in early spring produced the best yields at Cranford while timing of application had no significant effects on yields at Pincher Creek. Differential responses to timing have also been demonstrated in Saskatchewan, where time of application was found to influence winter wheat yields in only 7 of 21 different site locations (Fowler and Brydon 1989). Differences in method of application were apparent at Pincher Creek, where point injected N produced small but significant yield increases over BC methods. These yields differences are likely due to placing the N directly in the rooting zone where it is immediately available for plant uptake. Surface applied N is dependant on timely rainfall events to move the N into the rooting zone. Therefore, its' availability may not correspond to times of high plant requirements. This was evident in the late spring applications at Pincher Creek, where the PI treatments produced an average yield of 4437 kg ha-l compared to an average of 3958 kg ha-l in the BC treatments. Seeding Late Fall 80 60 40 20 0 Broadcast 1m Point Injection Early Spring Late Spring 100 100 80 20 40 60 80 20 40 60 80 N rate (kg/ha) l'f rate (kg/ha) Figure 2. Influence of time and method of application on grain N uptake at Pincher Creek in 1988/1989. 30 Fertilizer use efficiency at Pincher Creek, as indicated by the difference in N uptake between fertilized treatments and unfertilized controls was also influenced by method of application. Averaged across times and rates of application, the crop removed 28% more fertilizer N from the PI treatments than from the BC treatments (eg. 25.8 vrs 20.2 kg ha-l). This corresponds to fertilizer recoveries of 43 and 57% for the BC and PI treatments, respectively. In the PI treatments, the % recovery of applied N at seeding, late fall, early spring and late spring averaged 39, 50, 55 and 84%, respectively. This increase in recovery of fertilizer N with delay in application agrees well with earlier lSN studies investigating point injection (Janzen unpublished data). The increased fertilizer efficiency in the later application times likely reflects reduced leaching, immobilization and leaching losses (Malhi and Nyborg, 1983; Powlson et al. 1986). After one year of study and with only N uptake data available for one site, the results of this investigation are not conclusive, however they do suggest that PI may be a viable method of fertilizer application in winter wheat The advantage of timing application to suit crop growth requirements and available moisture conditions, and the potential for improved fertilizer use efficiency will potentially enhance winter wheat production and ease environment concerns associated with over-fertilization. References Alberta Agriculture. 1987. Average analysis of Alberta feeds 1976-1986. Agdex 100/81-6. Christensen, N.W. and V.W. Meints. 1982. Evaluating N fertilizer sources and timing for winter wheat. Agron. J. 74: 840-844. Grant, C.A., E.H. Stobbe, and G.J. Racz. 1984. The effect of N and P fertilization on winter survival of winter wheat under zero-tilled and conventionally tilled management. Can. J. Soil Sci. 64: 293-296. Grant, C.A., E.H. Stobbe, and G.J. Racz. 1985. The effect of fall-applied Nand P fertilizer and timing of application on yield and protein content of winter wheat grown on zero-tilled land in Manitoba. Can. J. Soil Sci. 65: 621-628. Fowler, D.B. 1982. Nitrogen and phosphorus fertilization for successful winter wheat production. Publ. No. 473, Extension Division, University of Saskatchewan, Saskatoon, Saskatchewan. Fowler, D.B. and J. Brydon. 1989. No-till winter wheat production on the Canadian prairies: Timing of nitrogen fertilization. Agron. J. 81: 817-825. Harapiak, J.R., R.M.N. Kucey, and D. Flaten. 1986. Nitrogen sources and placement in wheat production. p. 87-136. In A.E. Slinkard and D.B. Fowler (eds.) Wheat 31 Production in Canada. Division of Extension and Community Rel~tions, Univ. of Saskatchewan, Saskatoon, Saskatchewan. Janzen, H.H., C.W. Lindwall, C.J. Roppel. 1990. Relative efficiency of point-injection and broadcast methods for N fertilization of winter wheat. Can. J. Soil Sci. (in · press). Keller, G.D. and D.B. Mengel. 1986. Ammonia volatilization from nitrogen fertilizers surface applied to no-till corn. Soil Sci. Soc~ Am. J. 50: 1060-1063. Mahli, S.S. and M. Nyborg. 1983. Sources and timing of spring topdress nitrogen on winter wheat in Idaho. Agron. J. 80: 648-654. Powlson, D.S., P.B.S. Hart, G. Pruden, and D.S. Jenkinson. 1986. Recovery of 15N-labelled fertilizer applied in autumn to winter wheat at four sites in eastern England. J. Agric. Sci. 107:611-620. Sharpe, R.R., L.A. Harper, J.E. Giddens, and G.W. Langdale. 1988. Nitrogen use efficiency and nitrogen budget for conservation tilled wheat. Soil Sci. Soc. Am. J. 1394-1398. Tyler, N.J., L.V. Gusta, and D.B. Fowler. 1981. The influence nitrogen, phosphorus, and potassium on the cold acclimation of winter wheat <Triticum aestivum L.). Can. J. Plant Sci. 61: 879-885. 32 

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Fertilizer-use efficiency of point injected N in winter wheat

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