Based on the article "Low yields from wheat production? Here's why" published on AgTech Finder, the primary reason for low wheat yields is the mismanagement of Nitrogen (N) availability relative to the plant's specific growth stages.

​According to Phil Clancy (CEO of Next Instruments), yield is only half of the diagnostic equation; the other half is grain protein levels, which act as a direct indicator of nitrogen uptake.

​Main Reasons for Low Yields

​The article identifies several scenarios where nitrogen availability or lack there of directly impacts yield:

1. ​Insufficient Nitrogen at Early Growth Stages: If nitrogen is lacking during the "tillering" and leaf emergence phases (up to growth stage DC30), the plant cannot develop enough heads. Once this stage passes, the potential yield is set; adding nitrogen later may increase protein, but it cannot recover the lost yield potential.

2. The Yield-Protein Correlation: Research from the NSW Department of Primary Industries (DPI) indicates that the "sweet spot" for optimum wheat yield is a protein level of approximately 11.5%.

​a. Low Yield / Low Protein: Caused by insufficient nitrogen during both the early growth and reproductive phases.

​b. Low Yield / High Protein: Occurs when there is a nitrogen deficiency during tiller development (limiting the number of heads), but sufficient nitrogen during the reproductive/grain-filling stage.

 3. ​Water and Nutrient Synergy: While nitrogen is the major driver of yield, it requires sufficient soil moisture to be effective. If water is available but nitrogen is insufficient, the yield will remain limited.

4. ​Lack of Real-Time Data: Historically, farmers relied only on yield maps. The article argues that low yields persist because farmers haven't integrated real-time protein measuring (via on-combine NIR grain analyzers). Without a "Nitrogen removal map" (combining yield and protein data), it is difficult to see exactly how much nitrogen was extracted and where the soil was deficient.

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source: https://www.intechopen.com/chapters/56772

​To overcome low yields, the article suggests that nitrogen must be available at both the tillering stage (to set yield potential) and the reproductive stage (to realize that potential and reach optimum protein levels).

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Sources:

Clancy, P. (2025, July 23). Low yields from wheat production? Here's why. AgTech Finder. https://www.agtechfinder.com/agtech-info/low-yields-from-wheat-production-heres-why