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Fluid Journal : Fall 2014
14 The Fluid Journal Fall 2014 Table 1. Subplot treatments evaluated in the Sustainability Omissions Plot Design. The six subplot treatments are plant population, hybrid traits, N rate, other treatments, and crop protection inputs (fungicide). Trt. No. Trt. Pop Hybrid N Fert. Fungicide 1 HIGH TECHNOLOGY (HT) 45K MULTI-TRAIT BASE+SLOW REL MESZ STROBILURIN 2 -POPULATION 32K MULTI-TRAIT BASE+SLOW REL MESZ STROBILURIN 3 -HYBRID 45K REFUGE BASE+SLOW REL MESZ STROBILURIN 4 -NITROGEN 45K MULTI-TRAIT BASE MESZ STROBILURIN 5 -FERT 45K MULTI-TRAIT BASE +SLOW REL NONE STROBILURIN 6 -FUNGICIDE 45K MULTI-TRAIT BASE +SLOW REL MESZ NONE 7 TRADITIONAL (TRAD) 32K REFUGE BASE NONE NONE 8 +POPULATION 45K REFUGE BASE NONE NONE 9 +HYBRID 32K MULTI-TRAIT BASE NONE NONE 10 +NITROGEN 32K REFUGE BASE+SLOW REL NONE NONE 11 +FERT 32K REFUGE BASE MESZ NONE 12 +FUNGICIDE 32K REFUGE BASE NONE STROBILURIN formed quarter plots within each whole plot (Figure 1). The experimental design of the study is unbalanced because stover removal was not conducted in the corn/soybean (CS) system because most research agrees that stover removal in CS rotations is not an acceptable practice due to increased potential for soil erosion and soil organic matter depletion. Figure 1 demonstrates one replication (of four) of the study, illustrating the quarter plot design. Within each quarter plot, twelve split plots comprise the omission treatment study, as illustrated in Figure 1. All treatments were replicated 4 times. Treatments tested in the omission plot design are described in Table 1. A check strip block with no N fertilizer application was included in the design to assess nitrogen use efficiency (NUE) measures. Site-years. Due to the rotation treatment, two site-years are required for this study. Each year, one site is used to establish the "previous crops" (corn or soybeans) for the following year. The 2013 study was located at a site previously planted to either 10th year continuous corn or soybeans (in a long- term corn/soybean rotation). Soils were classified as predominantly Flanagan silt loam with tile drainage and without irrigation. Extensive soil samples were collected in the fall of 2010 to establish evenness in fertility levels and to make fertilizer recommendations. A potassium application was made in the spring of 2011. Stover removal, tillage, and P fertilizer applications were made in the spring of 2013. Fifty percent of the stover was removed by flail chopping all stover, raking into swaths, collecting and weighing it and replacing 50 percent, redistributing it evenly across plots with a manure spreader. Stover was not chopped in the CC treatments in order to better represent growers' field conditions and eliminate unnecessary equipment traffic and related compaction. This created a discrepancy between the CC and CCRM treatments, since the chopped stover replaced in the stover removed (CCRM) treatments was subject to being blown about by wind and was also likely to decompose faster than in the CC plots where stover was not chopped. Micro-essentials SZ (a fertilizer with N-P- K-S---Zn formulation 12-40---0-10-1 from the Mosaic Company) was band-applied with a tool bar in conventionally tilled treatments at the same time that tillage occurred. Planting. The 2013 planting season was wet and resulted in late planting dates throughout Illinois. The study was planted on June 19th with Syngenta hybrid N63R (109 days) 3000GT (with corn rootworm and corn borer resistance and Cruiser Extreme 250) or GT (refuge hybrid with Cruiser Extreme 250 without insect protection). Applications. N was broadcast-applied by hand as SuperU (Treatments 1, 2, 3, 5, 6, and 10) or sprayed in-row as urea ammonium nitrate (Treatments 3, 7, 8, 9, 11, and 12 [Table 1]) soon after planting. A sidedress N application of 60 lbs N as urea with Agrotain was applied at V4 to Treatments 1, 2, 3, 5, 6, and 10 (Table 1). Strobilurin fungicide was applied to select treatments at VT. Aboveground plant biomass samples were taken at R6 October 14-16 and grain was harvested a few weeks later. Root samples were collected during the first week of December. Roots were collected by running a large, custom-built U-shaped attachment approximately 16 inches deep over the center two rows in each plot to loosen soil around the root balls. Four roots were collected from each row. Roots were stored in a covered area outdoors at freezing or colder temperatures in onion sacks for up to four weeks until they could be washed, weighed, and ground. Soil moisture was monitored continuously all season using John Deere soil moisture sensors operating on the principle of heat capacitance. Four sets of soil moisture sensors were placed in the TRAD technology treatments of a single replication (Rep 4) in the CC/ Stover Retained/ Conventional Tillage, CC/Stover Retained/Strip Tillage, CS/ Conventional Tillage, and CS/Strip Tillage treatments in order to test the effect of Tillage (Conventional vs. Strip Till) and Rotation (Continuous corn vs. Corn Soybeans) on soil moisture. Each set of soil moisture sensors contained four individual sensors measuring soil moisture at 4, 8, 12, 20, and 40 inches below the soil surface. Sensors were carefully placed within the crop row and between corn plants to better indicate soil moisture conditions experienced by corn roots. 2011 Fungicide application and hybrid with insect resistance traits were less effective than fertility (N, P, S, and Zn applications) for increasing yields in 2011. Strip tillage performed as well as conventional tillage in corn-soybean rotations, but did not produce corn yields equivalent to conventional tillage in continuous corn production systems. Yield results