Miller Magazine Issue:114 June 2019

81 ARTICLE JUNE 2019 of the following sources of data: soils, crops, nutrients, pests, mo- isture, or yield, for optimum profitability, sustainability, and pro- tection of the environment (adapted from Precision Ag. 2003).” Since 2008, there has been approximately 10% increase in pro- duction shown in the following plot of annual gross grain produc- tion. So what is the next big step in PA that will sustain this growth rate? This article describes the Missing Piece of the PA Puzzle: Protein Monitoring, as the next big PA technology improvement. History of PA: The history of Precision Agriculture goes back to 1990 when GPS became available for public use. Since then the major techno- logy milestones include Yield Monitors, Auto steering, Controlled Traffic, Touch Screen Computers and Moisture Sensors. The end game for Precision Agriculture is Variable Rate Fertilization app- lications for nutrients including Nitrogen, Sulphur, Potassium and Phosphorous, yet so few farmers have adopted VRF technologies. The most likely reason for the low take up of VRF technologies is that there have been few examples of success that can be credited to PA. It could also be argued that farmers find it too complex to translate data taken from their PA tools to VRF prescriptions to use on seeders, spreaders and sprayers. The next piece of the PA Puzzle, i.e., On Combine NIR Analy- sis, offers a simple solution to the generation of VRF prescriptions based on using protein and yield maps to identify zones where plant growth and development has been limited by the amount of nutrients applied to the plants in the form of fertilizers. Description: On Combine NIR Analysis is a technology whereby protein, mo- isture and oil in grains and oil seeds are measured in real time as the combine harvests the grain from the field. Proteins are composed of Carbon, Hyd- rogen, Nitrogen, Sulphur and Oxy- gen. Specifically proteins contain approximately 17.5% Nitrogen and 3.5% Sulp- hur by weight. As such for every tonne of grain or oil seeds harvested from the field between 15 and 30kg of Nitrogen and 3 to 7kg of Sulphur are removed from the soil in the form of protein in the seeds. Based on these relationships between Protein and Nitrogen and Sulphur in the seeds, then the On Combine NIR Analyser provides a means of measuring Nitrogen and Sulphur availability and uptake across the field. Moisture is the major factor that influences plant growth and development however Nitrogen is the most important nutrient that is required by plants in order to fully grow and produce seeds. Figure 2 shows the growth stages of cereal crops such as wheat and barley. Nitrogen is required at all stages of the plant growth cycle and the majority of the Nitrogen is taken up during the Stem Elongation and Leaf Formation stages. However soil Nitrogen is critical at the Emergence stage because the plant needs Nitrogen for Tiller production. The number of Tillers should be between 6 and 8 in a healthy plant. If there is insufficient Nitrogen available in the soil at the Tillering stage, then the plant will produce less Tillers, i.e. 2 - 4. The number of Tillers dictates the number of stems and thereby heads of grains. Once the plant reaches the Stem elonga- tion stage, then the plant cannot produce more Tillers or stems. The Yield Potential is set by the number of Tillers that growth to produce stems and heads, and no amount of Nitrogen is going to increase the Yield beyond what can be achieved through the available Tillers. As the stems grow and leaves emerge Nitrogen and Sulphur are required in the process of photosynthesis to produce sugars which the plant needs to drive cell production and thereby bi- omass. The Flowering stage is where the heads emerge and are pollinated. If there is insufficient Nitrogen available at this stage the plant may abort some heads in order to ensure that whatever Nitrogen is available will be used to see seeds grow and release. The last stage is the Filling of the seeds. If there is enough Nitrogen available then the seeds will fully develop with starch and protein. If there is excess Nitrogen then the Fig. 2. Implementation of PA on combine harvesters since 1990.