Corn Response to Timing of Water Application

Transcription

1 Background Due to declining groundwater levels in Ogallala Aquifer, primary source of irrigation water for much of Great Plains, farmers in this region are facing reduced pumping capacities and restrictions on amount of water y are allowed to pump in a season. When available water is not enough to meet crop demands throughout growing season, it becomes critical to know when is most effective time in crop s life cycle to apply irrigation to maximize yield potential and profits. This study was designed to demonstrate importance of irrigation timing on corn yield potential. Research has shown that grain yield losses related to water stress are greatest when stress occurs during early reproductive stages, tasseling (VT) through milk stage (R3), while water stress after dough stage (R) has less of an impact. 1,,3 One study showed that a single irrigation omission during tasselling and ear formation growth stages could cause a 3 to % grain yield loss during a dry year. Much greater losses during a dry year of to 93% could be expected as a result of prolonged water stress during se sensitive growth stages. 3 Study Guidelines Nine corn products with relative maturities (RM) ranging from 9-1 RM were planted on May,. The field was planted to soybeans previous season. Spring strip-till and season-long weed control was conducted in all plots. All corn products contained insect protection traits. Monsanto Learning Center at Gonburg, NE Treatments Water was applied through a drip irrigation system with following treatments: No irrigation (dryland control) 3 inches applied before V (early) 3 inches applied at VT (appropriate timing) 3 inches applied at R3 (late) Each treatment was replicated 3 times. Results Precipitation and Soil Moisture During growing season, precipitation was adequate during vegetative growth stages resulting in limited stress, but precipitation was inadequate during reproductive growth stages (VT-R3) resulting in moisture stress. Precipitation, irrigation, and soil moisture was recorded for each treatment: Dryland (Figure 1). Soil moisture reached Maximum Allowable Depletion (MAD) level at V growth stage, indicating moisture stress throughout most of reproductive stages. 3 inches before V (Figure ). Applying irrigation prior to V growth stage resulted in less moisture stress early in reproductive stages as compared to dryland control, but it still allowed soil moisture to drop below MAD level just after VT growth stage. 3 inches at VT (Figure 3). Applying 3 inches of water at VT growth stage allowed soil moisture to very closely mirror MAD level and provided least amount of stress in early reproductive growth stages. 3 inches at R3 (Figure ). In this treatment, soil moisture remained below MAD level during early reproductive stages causing moisture stress during se critical periods.

2 Monsanto Learning Center at Gonburg, NE Dryland V VT R3 Total Water Storage at Field Capacity Figure 1. Water chart for dryland control. 3 Inches Before V V VT R3 Water Storage at Capacity Figure. Water chart for 3 inches before V treatment.

3 Monsanto Learning Center at Gonburg, NE 3 Inches at VT V VT R3 Water Storage at Field Capacity Figure 3. Water chart for 3 inches at VT treatment. 3 Inches at R3 V VT R3 Water Storage at Capacity Figure. Water chart for 3 inches at R3 treatment.

4 Monsanto Learning Center at Gonburg, NE Results Yields The dryland control received greatest amount of water stress during reproductive growth stages and resulted in lowest yields (Figure 5). Applying 3 inches of water at VT growth stage resulted in minimal water stress and highest average yields in study. Applying 3 inches of water at R3 growth stage provided lowest yield benefit of irrigation treatments. Corn yield in this treatment did benefit from 3 inches of water compared to dryland control. These results show impact that irrigation timing can have on yield. A return of as much as 19 bushels per acre over dryland yields can be achieved with each inch of water when applied at VT growth stage (Figure ). In terms of profit, based on a market value of corn of $3.5 per bushel, this study showed that a return of as much as $7. per acre can be possible with each inch of water when applied at VT growth stage (Figure 7). This is not net return, which can be determined by subtracting irrigation costs from yield profits. Yield (bu/acre) 1 Legal Statements The information discussed in this report is from a single site, replicated research or demonstration trial. This informational piece is designed to report results of this demonstration and is not intended to infer any confirmed trends. Please use this information accordingly. Individual results may vary, and performance may vary from location to location and from 15 Figure 5. Yields by irrigation treatment. 19 Key Messages Yields by Treatment This research reiterated results of previous research and showed that corn yield loss related to water stress can be greatest when induced in early reproductive growth stages. This study showed that a small amount of water at critical timeframe can have a substantial impact on corn yields. A return in yields of as much as bushels per acre per inch of evapotranspiration have been reported for corn. This study showed that, when applied at critical timeframe, each inch of water could result in a yield increase of as much as 19 bushels per acre. Sources: 1 Payero, J.O., Tarkalson, D., Irmak, S., Davison, D., and Petersen, J.L. 9. Effect of timing of a deficit-irrigation allocation on corn evapotranspiration, yield, water use efficiency and dry mass. Agricultural Water Management vol 9: Results from rainout shelter. Gonburg Learning Center Summary. Technology Development & Agronomy. 913EJP. 3 Cakir, R.. Effect of water stress at different developmental stages on vegetative and reproductive growth of corn. Field Crops Research vol 9: 1-. Sadras, V.O., Grassini, P., and Steduto, P. Status of water use efficiency of main crops. SOLAW background matic report-tr7. FAO. Dryland 3 in. before V 3 in. at V T 3 in. at R3 Treatment LSD (.) 15. year to year. This result may not be an indicator of results you may obtain as local growing, soil and wear conditions may vary. Growers should evaluate data from multiple locations and years whenever possible. Leaf Design is a registered trademark of Monsanto Company. Monsanto Company CAM 171

5 Monsanto Learning Center at Gonburg, NE Return (bu/acre) per Inch Water Applied 1 Return in Yields per Inch of Water as Influenced by Application Timing 15.9 Dryland 3 in. before V 3 in. at VT 3 in. at R3 Treatment Figure. Return in yields per inch of water over dryland control. Return ($/acre) per Inch Water Applied $ $7 $ $5 $ $3 $ $ $ Return in Dollars per Inch of Water as Influenced by Application Timing Dryland 3 in. before V 3 in. at VT 3 in. at R3 Figure 7. Return in dollars per inch of water over dryland control. Treatment