On Midwestern farms, profitability is heavily influenced by the choice of crop genetics. Every year, growers must decide among the hundreds of hybrids and varieties on the market. Further, biotechnology and market pressures have reduced the product cycle of corn and soybean seed. In the past, a corn hybrid might have been marketed for eight or nine years before being replaced. Today the average corn hybrid is only on the market for three years. Thus, farmers need to make seed decisions, and they need to make them quickly. Keeping that “tried and true” hybrid or variety may make them uncompetitive in today’s highly competitive farm economy. This article reports on a recent study of how Indiana growers use yield monitors to help make seed decisions.

Worldwide, the use of combine yield monitors has been growing steadily for the last 10 years. In the US, estimates indicate that 46 percent of the corn acres and 36 percent of the soybean acres will be harvested with combines equipped with yield monitors in the 2003 harvest. Some studies suggest that if yields can be increased one bushel per acre by better choice of genetics, the cost of the yield monitor and global positioning systems (GPS) can be repaid with the first year of yield data.

Manufacturers, agribusinesses, and researchers have made many suggestions about how farmers should use their yield monitors, but there is very little information on how farmers actually use yield monitor information in choosing hybrids and varieties. Recently, we did 10 cases studies of Indiana farmers to better understand the role of yield monitor information in hybrid and variety selection. We were particularly interested in identifying differences in the seed decision-making between farmers using and farmers not using yield monitors. We chose to do case studies, instead of a random survey, to facilitate a detailed look at farmer practices. Case study results cannot be generalized, but they provide in-depth information that helps us better understand why people do certain things.

Farmer Collaborators

We identified several potential Indiana farmer collaborators through Purdue Extension county educators. Then, we conducted a preliminary telephone interview was conducted to find out whether their farming operations fulfilled the conditions required for the study. We selected five farmers using combine yield monitors and five not using them. All yield monitor users in the study also had Global Positioning Systems (GPS).We conducted a semi-structured inter-view with each of these 10 farmers. The interview covered five main topics: 1) information used in seed selection, 2) aids to the decision, 3) decision timing, 4) yield stability assessment, and 5) yield monitor role in seed decision-making. A section of the interview was open to allow farmers to raise issues they believed relevant. Some characteristics of the farming operations studied are presented in Table 1.

In our study, farms with and without yield monitors were very similar, although yield monitors tended to be used on slightly larger farms where the cost of monitoring could be spread over more acres.

Table 1. Some Features of the Farms Studied

Information Used in Choosing Hybrids and Varieties

All case-study farmers depended on seed dealer recommendations to help them identify hybrids and varieties worth considering. They all used public yield information from university trials and other demonstration plots to help narrow the list of candidates, albeit to different degrees. One important difference was relevant distance from their home farm. Most of the case study farmers used data from neighboring areas of the nearest state to compare hybrid and variety performance, but all of them assigned the most weight in decision-making to trials close to their farms and operated under their farm conditions. Some producers gave an absolute priority to on-farm performance. For example, if a given variety had a low yield on their farm, they would not purchase it again regardless of how well it performed elsewhere. In situations like these, the main value of yield monitor information is that it shows variety performance in farmers’ own environment.

Decision Aids

Producers looked mainly at ranking of averages within trial sites to identify top-performer hybrids or varieties for that location. Average yields can be obtained in a variety of ways: scale, scale tickets, and weigh wagons. However, these methods can become time consuming during the busy harvest days. This is especially true when farmers do not own a weigh wagon and have to wait several days to use one from a local agribusiness. Farmers noted that a yield monitor can provide information with little disruption

to harvest progress.

Decision Timing

Farmers interviewed order most of their seed, especially corn, before December 31. Several of them order seed for the next year even before the current year’s harvest. This gives them priority in obtaining both hybrids in high demand and substantial seed price discounts. Another motivation for early ordering is that the purchase becomes a tax deduction for the current year. Most university and other trial results are not posted before mid November. For the earliest orders, yield monitor data is not of much use, but yield monitors can provide information about variety performance immediately after harvest, when most publicly available trial results are yet to be published.

Yield Stability Assessment

All 10 farmers were concerned about yield stability of the hybrids and varieties they choose for their operations, yet none of them had a formal method to evaluate it. At most, they eyeballed the frequency at which each hybrid or variety is at the top of the rankings in test plots. Yield monitors can provide information on yield variability within fields and between fields within a farming operation.

Yield Monitor Role

In the farms we studied, yield monitors played an important role in measuring on-farm variety trials. Most of the farmers using yield monitor have dropped the use of other methods to measure trials (e.g., weigh wagons, scales and scale tickets). Probably, this is because yield monitors are more time efficient than these other methods, and any lost of time during the harvest period can be costly. Most producers in our sample preferred to conduct on-farm trials laid out in the form of big blocks, rather than strip trials. They explained that blocks were less time consuming.

Farmers using yield monitors complained about yield maps. Producers said that yield maps were confusing to interpret and that they find it difficult to draw conclusions useful to crop management based on those maps. Often, visual map interpretation is of limited use in choosing hybrids and varieties. Default color code increments are often not small enough to detect important yield differences. Yield mapping software facilitates calculation of average yield and moisture for areas within fields (e.g., soil types). The case study farmers rarely took the time to do such calculations, but in some areas this is done by crop consultants or seed dealers as part of their customer service.

Almost all of the farmers using yield monitors identified their on-farm trials as one of the main sources of quantitative information for seed decision-making. However, none of the five producers not using yield monitors mentioned their own trials as an important source of quantitative information. With the use of yield monitors, case study farmers saw on-farm trial results as more valuable. This is probably because producers using yield monitors are able to collect more yield observations which tends to make their trial results seem more reliable.

Doing Better

The case studies suggest how the seed decision making process could be improved. First, an easy-to-use method for assessing yield and return stability for alternative hybrids and varieties is needed. This method should incorporate use of yield monitor data. It should also help growers put the data from their farms into a larger context. Some farmers drop a variety if it gives a low yield the first year on their farm, but this absolute preference for on-farm data may lead to new hybrids or varieties being dropped because of unusual conditions. Recent research suggests that estimation of yield and return distributions using public data from demonstration plots and university trials, as well as yield monitor data, and comparison of those distributions using risk analysis tools may help growers get a handle on yield and return stability.

Growers need better ways to extract crop management information from trials laid out in the form of large blocks. They prefer large block comparisons because they facilitate planting logistics, but they question the reliability of the information because of the lack of replication. Possibly, taking into account the spatial structure of the observations from the yield monitor can help distinguishing yield differences due to true genotype effects from those due to the internal variability of the blocks.

A remote sensing-based “early warning system” with yield estimates in August might help those farmers who ordered seed before harvest. Finally, yield map interpretation remains a constraint to better use of on-farm information. Farmers interviewed often mentioned that yield maps create more questions than answers. Better software can help, but the key to yield map interpretation is developing spatial analysis skills. Some farmers will decide to learn these skills them-selves; many more will probably hire that expertise.