Effect of liming materials on soil available nutrients, yield, and grade distribution of double-cropped tomato and cucumber grown with plasticulture

For economical reasons, cucumber (Cucumis sativus L.) may be grown as a dou ble crop after tomato (Lycopersicon esculentum Mill.). In this production s ystem, plant nutrition may be limited for the second crop due to pH change or insufficient levels of calcium or magnesium. The objective of this 2-yea r field study was to compare the effects of selected liming materials on yi eld and grade distribution, and soil available nutrients of a tomato/cucumb er double crop produced with plasticulture. Liming materials were compared to a control and a CaSO4 treatment based on the same neutralizing value as standard agricultural limestone. Supplemental N fertilization was provided by weekly injections at a rate of 7 kg/ha/week from ammonium nitrate (NH4NO 3) or calcium nitrate [Ca(NO3)(2)]. Each year, soil samples were collected at the beginning of the study and after each crop to determine nutrient ava ilability. All liming materials raised soil pH in 1998 and 1999 over the un limed control, though not to the target level for tomato and cucumber produ ction (pH 6.5). Throughout the study, agricultural limestone, a high CaO-co ntaining blend (calcitic blend) and a CaO/MgO (dolomitic blend), resulted i n greater fruit weights compared to the control and CaSO4. These materials, along with quick lime (CaO), provided higher levels of soil Ca and Mg avai lable for plant growth. However, it was found that current recommendations for potassium (K), regardless of liming source, were not adequate for optim al soil reserves and yields in this tomato/cucumber cropping system. Ammoni um nitrate as a source of N for fertilization was as effective as Ca(NO3)(2 ).