How Weather Affects Crop Yields

What it is like to be a Field Scientist at Corteva Agriscience - Week 22 Drought conditions and NuTech Seed, LLC visit It is HOT out there! This week we reached the hottest temperatures of the year in Iowa. The last time Cedar Rapids, IA reached 100 degrees was on August 30, 2013. Almost 10 years ago! The combination of high temperatures and high humidity leads to a heat index above 110. Gloria Melotto Rachel Rowan and I had a few time-sensitive field tasks and we were able to get them done very early in the morning safely before the heat of the day arrived! #safety  Besides the high temperature, it is also very dry. The U.S Drought monitor shows that we are under severe drought and some regions of the state are experiencing extreme drought. It is not just us that is struggling, but also our crops. Our experiments are around R5 stage, which means that all or nearly all kernels are dented or denting at this point. Kernels should have about 55% moisture content and going through drought stress during this stage causes yield reduction by reducing kernel weight. Farmers (and us) are in desperate need of rain. According to Pioneer field agronomists, because of the severe drought conditions, we are expected to have a decrease of almost 43 bushels per acre in 2023 for our region in Iowa. We are monitoring our trials closely because the drought can cause many other problems. One of them is the depletion of sugar in the stalk that can contribute to early death and poor stability. Even though we want and need rain, stalk rot and ear rot pathogens can invade and grow rapidly if moisture returns quickly. In drought weather, there is also a possibility of insect outbreaks, spider mites and grasshoppers can become a problem in corn and soybean, monitoring these outbreaks is also part of our work. Even though grasshopper will unlikely cause yield reductions, spider mites can be a big headache. As field scientists, it is part of our work to closely monitor all these issues and take appropriate notes and measurements to ensure the data was affected by external factors and not what we are actually testing. It was also a good week to learn about the hybrids that Corteva develops and help farmers to overcome issues like drought, among so many others we have commented on in the past. This week the Eastern Iowa NuTech Seed, LLC sales visited the station to learn from David Fischer (Corteva Agriscience corn breeder) how corn hybrids are developed and the long, complicated process it takes until it gets to a bag the farmer will buy. They also visited the demo plots to review the 2024 NuTech hybrid lineup that I have here in the photos. You all know I am an Entomologist, corn breeding is a hard subject for me, so if you have any questions about it, go ahead and ask Dave Fischer, he is one of the most experienced breeders out there =) #keepgrowing #LifeatCorteva #InnovateBoldly

THE RELATIVE IMPACT OF CROP WEATHER VARIABLES ON THE U.S. AVERAGE YIELD OF SOYBEANS by Scott Irwin SUMMARY: Whenever there is a wide range of weather conditions across time and space, as there has been this year, there is a great deal of interest in which weather variables were the most important in determining soybean yields. While there is a general understanding of the importance of different weather variables on soybean yield, there is less understanding about the relative magnitude of such impacts. In this article, a crop weather model is used to estimate the relative impacts of important weather variables on the U.S. average yield of soybeans. The crop weather regression model uses data for 1980 through 2022 to relate the U.S. average soybeans yield to a time trend, the percentage of the crop planted late, and an array of weather variables. We then consider a one-standard deviation range in impact for each of the crop weather variables to standardize for differences in the variation of each variable. The analysis shows that the “big three” for determining the U.S. average yield of soybeans are August precipitation, July precipitation, and late planting, with August precipitation just edging out July precipitation for the top ranking. About two-thirds of the time, the impact of either August or July precipitation on the U.S. average yield of soybeans is in a range of slightly more than two bushels per acre. Hence, both August and July precipitation are “golden numbers” for U.S. soybean yields. LINK: https://lnkd.in/gKVEZMg7 #soybeans #production #weather #planting #cropyield #cropsupply

Farming, especially regenerative organic farming, is not for the faint at heart and wouldn’t be nearly so challenging if we had even a little control over the weather. Last week we replanted corn due to drought conditions causing roughly only 10% of the kernels to sprout and grow. Until last week, we had not a soil moistening rain for nearly 12 weeks. Planting into the rolled down biomass of winter cover crops only amplified the challenge due to decreased seed to soil contact caused by hair pinning and dry hard soil. In hindsight, we should have waited to plant till we received some rain to have sufficient soil moisture which would have allowed for better seed placement and moisture to get the crop sprouted and off to a good start. Note in the picture the few lonely surviving corn stalks. The timing of rolling down/terminating the winter cover crop is without flexibility and you can also see in the picture that may be the only thing we got right this year, lol. We have a nearly 100% termination of the winter cover crop (without viable seed development) in the roll down process and with the thick mat covering all the soil will be able to hold moisture much longer. On the bright side, the replant looks good, and it is only the first of July which should be sufficient time for the newly planted 93-day maturity corn to fully develop. Consulting with several other organic crop producers, they said that more times than not, the replant turns out to be their better yields. I can see how that is possible due to proper soil moisture allowing for improved seed placement and with the rolled down biomass having a few weeks to dry down, we saw an improved ability to penetrate the mat with minimized hair pinning. And so far, thanks to a strong cover crop yield, the mat is holding the weeds back sufficiently but losing a valuable month of growing season, we just hope it holds until the corn canopies. I will report on the crops sprouting success and weed pressures when the corn is around the v4/v5 stage. Until then, cheers and chin up to all the farmers facing challenging conditions this year!  #regenerativefarming #quicklyadapt #persistance #alwayslearning

In my ongoing research on the effects of drought and irrigation on crop health, I’ve recently taken some thermal images of my field that clearly illustrate the stark contrast between drought and irrigated conditions. These images reveal a significant difference in temperature between the two areas, with the drought-stressed sections showing noticeably higher temperatures compared to the irrigated ones. This phenomenon is particularly concerning, as higher temperatures in drought-affected areas can exacerbate stress on the plants, leading to increased rates of flower and pod abortion, reduced yields, and overall poorer plant health. In contrast, the irrigated areas maintain lower temperatures, providing a more favorable microenvironment for plant growth and development. The thermal camera images serve as a powerful visual tool to highlight the critical importance of adequate irrigation, especially during periods of high temperatures. These findings reinforce the need for effective water management strategies to mitigate the adverse effects of heat stress on crops, particularly in regions prone to drought. As the climate continues to change, understanding and addressing these challenges will be crucial for sustaining agricultural productivity and food security. Stay tuned for more updates from my field research! #cropmangment #irrigation #soybean #flowerabortion