measures: controlling lorry access and parking, installing special curtains to protect against window glass fragmentation, and so on.
The British view their approach to preventing bombings as one of making bombing increasingly inconvenient. They try to stay one step ahead of bombers in technology and also try to make the materials even harder to use. They acknowledge that this is only a delaying tactic and cannot prevent determined bombers from succeeding on occasion.
Modifying AN fertilizer to make it less explosive requires much more than finding a workable technique. Fertilizer use is a complex subject involving economics and soil and crop characteristics. Different crops need to be supplied with different nutrients, and fertilizer must be adjusted to match crop requirements to soil type. As a result, an increasing trend in the fertilizer industry is to tailor compound fertilizers to meet a farmer's specific needs. One approach is to encourage this trend, licensing a limited number of wholesalers to store (securely) undiluted AN and sell it only compounded and made to order.