Effect of Strip Tillage on Corn Nitrogen Uptake and Residual Soil Nitrate Accumulation Compared with No-Tillage and Chisel Plow

Kucey and Schaalje, 1986; Reeves et al., 1993; Randall et al., 1997; Torbert et al., 2001). Tillage and N management systems can have a significant effect Many soil and water quality problems are associated on N use by corn (Zea mays L.) and nitrate (NO3–N) movement with conventional tillage, along with other problems that through the soil profile. Potential water quality and NO3–N loss probaffect water resources (Baker and Laflen, 1983; Mickellems associated with conventional tillage and fall-applied N have prompted this study. The objective is to evaluate strip tillage effect son et al., 2001; Zalidis et al., 2002). Tillage systems on corn N uptake and NO3–N movement through the soil profile have a significant effect on N dynamics by affecting N compared with chisel plow and no-tillage systems. The three tillage pools in the soil system. Soil disturbance during the tillsystems implemented in this study were strip tillage, no-tillage, and age process and the incorporation of surface residue chisel plow along with two N application timings (fall and spring) of increases soil aeration, which can increase the rate of 170 kg N ha 1 for corn in a corn–soybean [Glycine max (L.) Merr.] residue decomposition (McCarthy et al., 1995). This prorotation on two Iowa fields in 2001 and 2002. The three tillage systems cess impacts soil organic N mineralization whereby readwere implemented every year for both crops (corn and soybean). ily available N for plant use is increased (Dinnes et al., Crop response, N uptake, and other soil NO3–N measurements were 2002). Therefore, the type of tillage system and N fertilconducted on a randomized complete block design experiment. Grain ization timing can influence the amount of N available yields and grain N uptake showed no significant improvement under strip tillage compared with no-tillage or chisel plow systems. Tillage for loss in the soil profile. Deep accumulation of NO3–N and N treatments caused no significant differences in NO3–N accumuin the soil profile represents a potential for NO3–N leachlation at the lower depths of the root zone (1.2 m). Strip tillage and ing into shallow water tables (Keeney and Follett, 1991). no-tillage resulted in lower residual soil NO3–N buildup than chisel Halvorson et al. (2001) found that conventional and conplow in the 0to 1.2-m soil profile after 2 yr of tillage implementation. servation tillage systems accumulated more soil NO3–N Tillage and N treatments did not cause significant differences in down to 150 cm compared with a no-tillage system in a NO3–N concentration in water leachate collected at the 1.2-m depth. spring wheat (Triticum aestivum L.)–fallow cropping study in North Dakota. They concluded that conventional and conservation tillage systems mineralized more N at T integration of tillage and N management (i.e., the soil surface due to soil disturbance than their notype of tillage system, timing of tillage system, timtillage system. Similarly, Sainju and Singh (2001) found ing of N application, and N rate) present significant chalevidence that more intensive tillage systems caused lenges for producing corn, sustaining soil productivity, greater NO3–N accumulation in the soil profile than noand improving water quality. The susceptibility of N to tillage using corn and a cover crop. In a 3-yr study on leaching, denitrification, volatilization, and immobilizatillage and N management in a corn–soybean rotation, it tion is highly related to the timing of N application, which was found that moldboard plowing reduced tile flow by can increase due to fall N application compared with an average of 2 cm of water depth compared with nospring application (Dinnes et al., 2002). Fall N applicatillage (Weed and Kanwar, 1996). In the same study, the tion can lead to significant N losses, rendering it less 3-yr average NO3–N concentration of the tile water of effective for plant uptake. Delaying N application until no-tillage was lower (21.9 mg L 1) than that of moldboard spring can reduce NO3–N losses due to leaching and plowing (36.9 mg L 1), and the average NO3–N loss from surface water runoff (Malhi and Nyborg, 1983; Carefoot the no-tillage system was 74 kg ha 1 less than the moldand Janzen, 1997). The timing of N fertilizer application board plow system (Weed and Kanwar, 1996). Randall is one of many causes of nutrient losses into the nation’s and Iragavarapu (1995) found similar trends under conlakes and streams (Gast et al., 1978; Power and Schetinuous corn from an 11-yr study in southern Minnesota pers, 1989), hypoxia in the Gulf of Mexico (Dinnes et al., where the 11-yr average of NO3–N losses for moldboard 2002), and adverse health effects such as methemogloplowing were 43 kg ha 1 compared with 41 kg ha 1 for binemia (Fletcher, 1991; Keeney and Follett, 1991). In no-tillage losses. The narrow difference in NO3–N loss southern Minnesota, NO3–N losses into tile drains were between the two systems was attributed to the greater reduced by 36% with spring N application compared length of the study, which caused greater variability in with fall N application (Randall, 1997). Nitrogen losses the soil and environmental conditions. can create conditions where N becomes deficient and Total grain N content is often found to be greater crop productivity can decline rapidly (Welch et al., 1971; under no-tillage system due to greater N use efficiency in no-tillage crops than crops grown in conventional tillage Dep. of Agron., Iowa State Univ., Ames, IA 50011-1010. Received Abbreviations: DOY, day of year; FCP-FF, fall chisel plow with fall 26 Aug. 2003. *Corresponding author ([email protected]). N fertilizer application; FST-FF, fall strip tillage with fall N fertilizer application; FST-SF, fall strip tillage with spring N fertilizer applicaPublished in Agron. J. 96:1164–1171 (2004).  American Society of Agronomy tion; NT-FF, no-tillage with fall N fertilizer application; SST-SF, spring strip tillage with spring N fertilizer application. 677 S. Segoe Rd., Madison, WI 53711 USA