Can crop rotation and timely sowing reduce pests without sprays?

Yes, and these cultural methods are the cheapest and most powerful part of organic pest management because they prevent problems instead of reacting to them. Crop rotation breaks the life cycle of pests and soil diseases that build up under the same crop year after year, for example rotating away from a host crop starves soil grubs, nematodes and wilt fungi. Timely sowing lets the crop pass its tender stage before the peak pest flight arrives, or escape it, so early or recommended sowing dates often cut borer and sucking pest damage sharply. Other free practices that help, choosing resistant or tolerant varieties, proper spacing and avoiding excess nitrogen which makes lush growth that sucking pests love, deep summer ploughing to expose soil grubs and pupae to the sun and birds, removing crop residue and weeds that shelter pests, and intercropping to confuse pests and host natural enemies. None of these gives a dramatic overnight kill, but together they lower the baseline pest pressure so much that your neem, traps and biopesticides have far less to do. This prevention first approach is the backbone of organic and IPM. Local timing and variety advice is best taken from your KVK.