Leaving Cert Agricultural Science Soil Science: Soil sampling for analysis is im

Question

Soil sampling for analysis is important to determine soil index and fertiliser requirements. 
Outline two procedures to be followed when taking soil samples for analysis.

1. Utilize a mini soil sampler or spade for consistent depth (to the recommended depth). 
2. Sample field areas separately, avoiding headlands and fertiliser application areas for a more reliable analysis.

(b) Below is a soil index reference sheet and two sets of soil sample results. Analyse the tables of results and answer the questions that follow.

(i) Determine the P and K soil indexes for field 2.

| Nutrient | Field 2 |
|----------|---------|
| P        | 3       |
| K        | 4       |

(ii) Suggest one reason why the P and K indexes in field 1 are very different to the P and K indexes for field 2.

Field 1 
Mainly used for silage production so there are no animals grazing the land so very little dung and urine or chemical fertiliser is on the land giving so little opportunity to build up P and K levels / pH is very low (5.3) which immobilises nutrients.

Field 2 
Main grazing block so there are animals grazing it constantly so there is dung and urine spread being added to the land allowing for increased P and K levels / pH is 6.0 (ideal) for nutrient availability.

(iii) Discuss the implications for the farmer of the low pH in field 1 in relation to liming and the uptake of nutrients.

Farmer needs to add 5 ton per ha lime to land / low pH 5.3 - reduced availability of nutrients to plants - reduced growth rates and decreased yield of crop / ions may become abundant in soil - may build up toxic levels / activity of micro-organisms may decrease as optimum for activity is above pH 6.0 / when pH moves above 5.5 - more nutrients become available - optimum crop growth pH 6.5.

(iv) Some macronutrients do not appear on the table. Identify any two other macronutrients and state their role in plant growth.

1. Sulfur - forms enzymes or assists in formation of plant proteins / closely associated with N uptake or efficiency.

2. Calcium - formation of cell walls or regulates growth etc.

(v) Outline two ways in which farmers can increase the K levels on their land.

1. Spreading slurry / FYM / any amended granular fertiliser (e.g. 10-10-20, 18:6:12, potash etc.) / green manure.

2. Create buffer or riparian zones around watercourses (especially in heavy rain) - establish native vegetation / biofilters etc.

(vi) Briefly describe two ways a farmer can prevent P leaching from the soil and potentially damaging water quality.

1. Use cover crops to retain nutrients and prevent run-off.

2. Implement buffer strips along waterways to filter runoff.

Soil sampling for analysis is important to determine soil index and fertiliser requirements - Leaving Cert Agricultural Science - Question 17 - 2021

Worked Solution & Example Answer:Soil sampling for analysis is important to determine soil index and fertiliser requirements - Leaving Cert Agricultural Science - Question 17 - 2021

Outline two procedures to be followed when taking soil samples for analysis.

Determine the P and K soil indexes for field 2.

Suggest one reason why the P and K indexes in field 1 are very different to the P and K indexes for field 2.

Discuss the implications for the farmer of the low pH in field 1 in relation to liming and the uptake of nutrients.

Identify any two other macronutrients and state their role in plant growth.

Outline two ways in which farmers can increase the K levels on their land.

Briefly describe two ways a farmer can prevent P leaching from the soil and potentially damaging water quality.

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