Maize production potential and climatic risk in the South Island of New Zealand

Abstract

Maize production is expanding in the South Island of New Zealand even though the climate is cool and variable, and marginal for reliable production of the crop. Its productivity in the region was assessed in field experiments conducted at Lincoln, Canterbury, during three contrasting seasons-two warmer and one cooler than average for the region. Three cultivars with different maturity characteristics were sown on several dates in each season. Even though the deviations from the longterm mean seasonal temperature (14.5°C) were quite small (-0.6 to +0.7°C) they had large effects on crop development and yield. Silage and grain yields were high (means 18.9 and 9.1 t/ha respectively) for all sowing dates of all cultivars in the warmest season, indicating good production potential in favourable years. However, in the other two seasons, yields were reduced in treatments that were sown late or where late-maturing cultivars were used. In the coolest season, some crops failed to start grain growth before the first autumn frost; their yields were low and they produced poor quality silage. The climatic risk of growing maize in the region was quantified by analysing historical temperature records from eight locations together with a simple thermal-time phenology model. Probabilities of failure to reach maturity were calculated for combinations of five cultivar maturities and four sowing dates spanning the ranges likely to be used in the region. The analysis confirmed that reliable maize silage or grain production is marginal because of variability in temperature and frost occurrence among seasons and the sensitivity of crop development rate to temperature. Crop failures are likely in cool seasons or when early autumn frosts occur, especially with late sowing or when late-maturing cultivars are used. Locations differed in their suitability for maize production. Areas in the north (represented by Riwaka and Blenheim) were the least risky, and were the only places where both grain and silage production appear to be viable. At lower altitude, coastal locations in central Canterbury (Rangiora and Lincoln), levels of risk were acceptable for silage crops, but the area was beyond the climatic limit for reliable grain production. Although some crops completed grain growth, they probably would not have reached an ear moisture content low enough for commercial machine harvesting of grain. Higher altitude, inland locations and areas further south were not suitable for reliable silage production because crops often failed to complete grain growth, even when earlymaturing cultivars were sown early.

The yield and nutritive value of maize hybrids grown for silage

“…The lack of correlation between biomass yield and biomass N percentage in the present study has been observed in earlier studies (Hunter 1986) and supports the contention that it may be feasible to develop hybrids with both high yield and high crude protein, although there is little genetic variation in this trait. The high percentage grain in the early maturing hybrids (Table 4) agrees with results obtained at Lincoln, New Zealand (Wilson et al 1994), and may be the result of increased time available for partitioning dry matter into the grain (Deloughery & Crookston 1979) in early hybrids and decreased radiation use efficiency resulting from lower average temperatures during grain-fill for later hybrids (Wilson et al 1995). Plant population had little effect on percentage grain, indicating that environmental conditions (moisture and fertility) were not seriously limiting during most of the growing season (Duncan 1975).…”

“…The biomass yields obtained ranged between 15 800 and 20 700 kg DM/ha, similar to the yields reported in Canterbury (Wilson et al 1994) in years with average or higher than average temperatures. Differences among hybrids generally reflected their maturity ranking (Graybill et al 1991).…”

“…The thermal times required between sowing and mid silking (Table 3) agree closely with those recorded by Wilson et al (1994) for P3902 and P3585 (717 and 830°C days, respectively) reinforcing the advantage of thermal time over chronological duration to predict crop development.…”

“…The relative performance of the hybrids in this comparison may vary with sowing date and environment. In cool seasons, and when sowing is delayed, the yield of later maturing hybrids will be reduced because the grain fill period is more likely to be curtailed due to low temperatures (Wilson et al 1994). Harvest dates in this trial ranged from 14 March (Janna) to 28 March (P3585), indicating that all of these hybrids are capable of reaching silage maturity in the Manawatu region in a normal season.…”

Aiming for 45 t/ha per annum: yield of supplementary feed crops grown in sequences designed for maximum productivity

“…A renewed interest in supplementary feeds such as whole crop silage (de Ruiter et al 2002;Milne 2007;Platfoot & Stevens 2002) maize silage (Dalley et al 2005;Densley et al 2005b) and brassicas (Hogg et al 2002) has been driven by the demand for higher per cow performance. Maize for silage has been considered in southern latitudes (Wilson et al 1994) with the main option being short maturing hybrids to reduce the risk of crop failure. Summer fed turnips (Eerens & Lane 2004) and grazing-type brassicas such as leafy turnips (2009) Proceedings of the New Zealand Grassland Association 71: [107][108][109][110][111][112][113][114][115][116] treatments in the second sequence (Sequence 2) in the autumn and winter of Year 1 (Table 1).…”