U.S. summer crops in the Midwest were hanging on relatively well during July and early August, despite late season planting delays and a cooler biased spring. Rainfall was restricted during the heart of summer in the western Corn Belt, but cool weather preserved much of the crop and kept yield potentials looking good. Much warmer temperatures and continued dry weather in late August turned that around, creating critically dry conditions in key western and central U.S. Midwest corn and soybean production areas forcing yields lower. The concern for dryness in the United States will continue into early September while other worries over dryness continue in Australia, Argentina, South Africa and West Central Africa.
Summer weather for 2013 will end up in the record books as just another perfect example of how production is far more influenced by temperatures than by precipitation. July weather was quite dry in the western Corn Belt, but temperatures were cooler than usual during the latter part of the month and into early August, reducing crop moisture demand and evaporation rates. Crops maintained themselves quite favorably during the milder period, keeping most of their production potential while the soil slowly dried down. Scattered showers and thunderstorms during mid-August also helped to curb the drying trend, but a ridge of high pressure over the middle part of the United States in the last week of August brought on more dryness and unusually warm weather, inducing significant crop stress.
Crop conditions have been deteriorating at a very fast pace ever since then, and with another full week of the same pattern lying ahead the fear is that soybeans, late corn and sorghum will all experience a significant decline in production.
Late August warm and dry weather affected much of the Midwest and surrounding crop regions. A reduction in soil moisture again was noted in the majority of the region. Eastern and southernmost portions of the Midwest still had favorable subsoil moisture at that time carrying on normal crop development in much of the region. However, many areas from central Illinois and parts of Indiana through northern Missouri and Iowa to the eastern Dakotas and Minnesota quickly turned critically dry in the topsoil and marginally adequate to short in the subsoil. Time was running out for crops to escape dangerous stress in the above drier areas, and all it needed was hotter temperatures. Temperatures in the last days of August rose well above average in many areas and that pushed crops over the edge and into a tailspin in production potentials that will not likely end until significant rain falls or crops become fully mature.
Topsoil moisture in much of the Midwest was short to very short near the end of the month. The greatest topsoil moisture remained in eastern Nebraska and far northwestern Iowa, as well as from southern Wisconsin into northeastern Illinois and in random locations from southeastern Ohio to eastern Kentucky. At this time of year, subsoil moisture is most important for crops. Very short topsoil moisture is not unusual, but having short to very short subsoil moisture while temperatures are warmer than usual may translate into serious stress and production potential reductions. Such conditions do exist today in quite a few areas in Iowa, northern Missouri, northwestern and central Illinois, west-central Indiana, portions of northern Michigan and in the eastern Dakotas and a part of Minnesota. Each of these areas likely is suffering from yield-reducing moisture stress, especially as soil temperatures rise.
Rainfall through the first week of September will be dismal in many central and western portions of the Midwest. Most areas from southeastern South Dakota into Illinois only will have a chance to receive up to 0.25 inch and locally greater rainfall. Any rain that does occur will not be enough to counter evaporation, and net drying conditions will continue. Subsoil moisture shortages gradually will intensify and expand. Crop stress will continue to evolve and outlooks for this year’s harvest will continue to deteriorate. North Dakota, Minnesota, Wisconsin and northeastern South Dakota will receive enough rain to keep soil moisture at favorable levels. There may be enough precipitation in North Dakota and Minnesota to cause a short-term increase in soil moisture, but evaporation rates will be too high for the increase in soil moisture to remain for an extended period of time.
The eastern Midwest also will struggle to receive a significant amount of rain during the coming week and in most cases also will experience net drying conditions. But there is enough moisture in the subsoil for favorable crop development to continue and the expected showers will help to slow drying rates.
Warm temperatures expected in the first week of September would be welcome had there been greater soil moisture available to crops due to the cool spring and lack of degree day accumulations in many areas. Limited soil moisture will allow the heat to only stress the majority of crops, raising further concerns about their production potential, especially for soybeans, which are in the their most moisture sensitive pod-setting and filling stages of development. Persistent heat and dryness at this time of year will reduce yields and oilseed quality. Corn is a little further advanced, and even though heat and dryness may reduce yields and quality the decline will be less significant than that of the soybean crop.
The only good news in the hot, dry, bias is that immature crops will be rushed to maturity in this environment. Unfortunately, that maturity will come at the expense of yields and quality. In time, the crop will likely become less vulnerable to frost and freeze damage. That seems like a silly statement since what is gained by having crops more mature when frost and freezes come along already will have been lost by heat and moisture stress reducing production while plants are rushed to maturation.
Australia wheat faces trouble again
Problems in U.S. crop development are mostly focused on coarse grain and oilseed production, but there are a number of other areas still facing potential problems with small grain production. Australia is high on the list, once again.
Late season frost and freezes were noted in the last part of August in Queensland and northern New South Wales while wheat was moving into reproduction, raising the potential for crop reductions. To make matters worse, crops in unirrigated areas of these two regions are suffering from prolonged dryness and reproduction is beginning. The prospects for rain through the first part of September are poor and the combined impact of recent frost damage with ongoing dryness likely will reduce yields.
To make matters a little worse, changes in the Pacific Ocean temperatures may generate El Niño-like conditions over the balance of this year suggesting some further dryness issues over time.
Argentina dryness still widespread
Poor rainfall since the start of winter wheat planting in late June has been prevailing in western Argentina. Crops in Cordoba, western Santa Fe and northwestern Buenos Aires have not had much opportunity to establish this winter and spring warming is just weeks away. Significant rain must begin falling soon to prevent dryness from threatening production.
Argentina is not nearly the wheat producer that it once was, but adding potential production issues from Australia, South Africa and Brazil makes the situation a little more interesting. Rain in the next few weeks may still make a huge difference to total production.
South Africa and Brazil
Southern Hemisphere production issues are nearly unanimous. Eastern portions of South Africa have not seen much rain during their autumn and winter planting season, and they need significant rain soon to avoid a notable cut in production. South Africa is not a major wheat producing nation, but its dryness is most interesting when added into all other dryness areas in the Southern Hemisphere.
Brazil’s wheat crop was damaged by frost and freezes this year. Parana, the nation’s most important production state, experienced a 34% cut in production because of late July freezes. Rio Grande do Sul and Sao Paulo also have had some light amounts of damage.