What fertilizer should I use for my yellow and slow-growing lawn, and where can I buy it in large quantities?

I have a 16-month-old lawn that appears yellow and is growing slowly. I'm considering applying fertilizer, but I'm not sure which one to choose. Also, the area that needs fertilizing is quite large, and I require around 30-40kgs. Can you suggest the best fertilizer to use, and where can I buy it in such large quantities?

Yellowing is common in new lawns, particularly if fertilizer was not applied before sowing. Lawns have been affected by drought in many areas due to patchy rain. For a large area, it is possible to use agricultural fertilizers such as 10-10-20 or similar, which is suitable for autumn use, and high nitrogen in spring and summer if necessary. 30g per square meter is sufficient, and it should be applied only when rain is anticipated. You can purchase such fertilizers in large quantities from agricultural suppliers or garden centers that stock agricultural fertilizers.