Effect of Corn, Sugarbeets, and Fallow on Zinc Availability to Subsequent Crops

Field observations indicated that Zn deficiency of beans (Plasscoins melons L.) was sometimes more severe than expected when grown on Mowed soil that was low to marginal in available Zn. The objectives of this study were to determine the effects of fallow, suprbeets (Beta Moods L.), and corn (Zea mays L.) on Zri availability to subsequent crops grown on a Portneuf silt loam (Durixerollic Calciorthids, coarse silty, mixed, mesic). The sugarbeet and corn plant tops and sugarbeet roots were removed, and 11.2 kg Zn ha' was applied on one-half of each plot before fall plowing 25-cm deep. Beans, sweet corn, or potatoes (Solomon tubers's:on L.) were planted the following spring. Whole plant samples of beans and sweet corn and potato stems, leaflets, and petioles were sampled for chemical analyses during the growing season. All bean plants were Zn deficient when grown after fallow or sugarbeets but not after corn or where Zn fertilized. Potatoes and sweet corn did not show any Zn deficiency symptoms or any growth responses to Zn fertilization. The average zinc concentration in beans (vegetative development stage, V3) following Corn was 20.5 mg kr , compared with 12.5 mg kg-' following fallow or sugarbeets without Zn fertilization. The average Zn uptake by beans (V3) following corn was 1.3 g ha-' compared with 0.6 g ha ' after fallow or suprbeets without Zn fertilization. The Zn uptake after corn was even greater than where 11.2 kg Zn ha ' was applied to fallow or sugarbeets (1.3 vs. 0.9 g Zo ha-'). Enhanced Zn availability following corn persisted throughout the growing season and into a second bean crop, although at a decreased level. Similar trends occurred with potatoes and sweet corn. Soil DTPA-extractable Tai was not significantly different after fallow, sugarbeets, or corn. These results indicate that Zn deficiency in sensitive crops may be alleviated or prevented depending upon the preceding crop grown, and that factors not measured by DTPA can significantly influence Zn availability. Additional Index Words: zinc deficiency, Phaseolus ralgaris L., Solon= mberossom L.. Zea mays L, nutrient recycling, root decomposition, chelation, DTPA-extractable Zn. Leggett, G.E, and D.T. Westerrnann. 1986. Effect of corn, sowbeets, and fallow on zinc availability to subsequent crops. Soil M. Soc. Am. J. 50:963-968. A PREVIOUS CROP of sugarbeets (Beta vulgaris L.) is recognized as a factor increasing the likelihood of Zn deficiency in subsequent crops. Zinc nutritional problems do not always arise following sugarbeets but they occur often enough to alert growers to the possibility. Boawn (1965) conducted a field experiment where sweet corn (Zea mays L.) was Zn deficient following sugarbeets but not following sugarbeets fertilized with Zn or sorghum (Sorghum bicolor L.). He concluded that sugarbeets had a deleterious effect on the Zn nutrition of subsequent crops. De Remer and Smith (1964) also mentioned the detrimental effect of sugarbeets on a subsequent crop of beans and indicated that returning beet tops to the soil aggravated the Zn deficiency problem. Boawn (1965) concluded that the presence of beet tops did not influence the results of his experiment. Zinc deficiency of beans (Phaseolus vulgaris L.) is common in southern Idaho where control measures have been recommended for many years (Brown and LeBaron, 1968). Several situations were observed where beans were more severely Zn deficient than expected when grown on followed areas that were marginal to low in available Zn. These observations were not from controlled experiments and it was not known if, or how, fallow affected the disorder. Irrigated fields are seldom allowed except where necessary for weed control or for other special problems. No literature citations were found that delineated the effects of fallow on the Zn nutrition of subsequent crops. The objective of this work was to determine the effect of fallow as compared to corn and sugarbeets on the Zn nutrition of subsequent crops. METHODS AND MATERIALS Three field experiments were conducted on a Portneuf silt loam (coarse-silty, mixed, mesic Durixerollic Calciorthids) near Kimberly, ID during 1980 to 1983. The treatments in each experiment differed, but several management operations were common to all. A zinc sulfate solution (34.5 g Zn was uniformly sprayed on the soil surface to give 11.2 kg Zn ha -' as the Zn treatment. Concentrated superphosphate (low Zn content) was broadcast according to the soil test (Olsen et al., 1954). Both materials were applied before moldboard plowing 25-cm deep. Nitrogen fertilizers were broadcast and worked into the surface 15 cm of the soil before seeding, except where side-dressed during the growing season. Irrigation water was applied in furrows according to tensiometers placed 45-cm deep in one crop row in each replication. The followed plots were irrigated at the same time and for the same duration as were the corn and sugarbeet plots during the differential cropping. At the end of the differential cropping season the corn was harvested for silage. The sugarbeets were machine harvested and removed from the plot areas along with their tops. Cropping treatments for the three experiments are summarized in Table 1.