## Stable yields despite 30% less fertilizer

### Field trials in OSR have shown a substantial saving potential regarding variable rate fertilizer applications using SKYFLD. The maps are easily generated, compatible with most on-board systems and adaptable to any preferred crop strategy in minutes.

A practical field experiment with a German farmer in North Germany compared the conventional broadcast fertilization to a variable fertilisation using SKYFLD variable rate application maps. In addition, it was examined how yield was affected by a 30% reduction in the total amount of nitrogen fertiliser both for broadcast application and for use of SKYFLD application maps.

As assumed, the reduced nitrogen rate lead to a decrease in yield level in both the conventional broadcast and the precision farming variant, where the usage of SKYFLD variable application maps resulted in higher yield for both 100% N and 70% N applications compared to conventional broadcast application.

Most remarkable is that the 70%N SKFLD variant performed as well as the 100%N fertiliser loading in broadcast application.

The utilization of SKYFLD variable rate application maps thus contributes to increased profits per hectare and as well as help coping with current pricing trends by reducing the overall amount of applied product.

Variant | Fertilisation strategy | Fertilisation rate | Autumn application | Spring application | Summer application | Winter application |
---|---|---|---|---|---|---|

1 | Uniform rate | 148 kg N/ha | 46 kg N (Urea) | 46 kg N (SSA) | 46 kg N (Urea) | 10 kg N (AHL) |

2 | Uniform rate -30% | 102 kg N/ha | 32 kg N (Urea) | 32 kg N (SSA) | 14 kg N (Urea) | 10 kg N (AHL) |

3 | Autumn and Spring application site specific | 148 kg N/ha | 46 kg N (Urea) | 46 kg N (SSA) | 46 kg N (Urea) | 10 kg N (AHL) |

4 | Autumn and Spring application site specific -30% | 102 kg N/ha | 32 kg N (Urea) | 46 kg N (SSA) | 14 kg N (Urea) | 10 kg N (AHL) |

The test area consisted of 4 stripe plots and an area of 2.59 to 3.35 hectares. All plots were set up between the tramlines resulting in 36 meters width. All variants were replicated resulting in a total test area of 24.58 hectares.

The yield expectation was 38 dt/ha rapeseed. Regarding the N-Min and the absorbed N-quantity, a nitrogen requirement of 148 kg/ha N was calculated for the field average.

In early November, N uptake was measured by weighing the superficial plant mass. The values varied between 0.5 and 3.8 kg of plant mass per square meter, which corresponds to an N-intake between 23 kg and 171 kg! After calculation of the underlying value of 50 kg, between 15 kg had to be deducted or -85 kg.

The biomass map revealed even more inhomogeneous areas in the field, proposing that some values of less than 0.5 kg of plant mass per square meter were conceivable.

### Formula for calculating the N intake in autumn in winter oilseed rape:

((Surface plant mass of 1m² * 45) -50) * 0.7 = Creditable/deductible the value of N fertilisation

**Example: ((3.8 kg * 45) – 50) *0.7 = 84.7**

Canopy development was well in November and therefore it was possible to reduce the N loading by 84.7 kg N/ha compared to the local practice.

### Fertilisation took place following normal commercial practice.

Application | Strategy | Target N / reduction | Intensity | Min. Biomass | Zones |
---|---|---|---|---|---|

1 | Uniform rate | 148 kg N/ha | 46 kg N (Urea) | 46 kg N (SSA) | 46 kg N (Urea) |

3 | Uniform rate-30% | 102 kg N/ha | 32 kg N (Urea) | 32 kg N (SSA) | 14 kg N (Urea) |

For yield assessment, each plot was harvested and weighed individually. During harvesting and unloading, samples were taken in parallel. The individual threshing areas had a size of 2.59 to 3.35 hectares, based on the 36m plot width.

The yield was then calculated by hectare and calibrated to 9% humidity.

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