extreme soil types (sand and silty clay loam) and two intermediate soil types (sandy loam and loam), and provided interval information for only 1 d of each week from late March to mid-October. Rainfall rule. Because the volume balance model is necessarily
Jeffery C. Kallestad, John G. Mexal, Theodore W. Sammis and Richard Heerema
Carl J. Rosen and David E. Birong
Recent demand for high-quality garlic (Allium sativum L.) has prompted an interest in growing garlic as an alternative crop in the Upper Midwest. The overall objective of this study was to determine the effects of various amendments on garlic growth and selected soil quality indices in two contrasting soils. Garlic (Rocambole type) was planted in the fall of 1995 on a Kandota sandy loam (5% organic matter) and a Spartan loamy sand (1.5% organic matter). Three treatments replicated three times were tested: 1) a nonamended control, 2) manure compost, and 3) fertilizer application based on a soil test. Scapes were removed on half the plants in each plot and allowed to grow until harvest on the other half. Soil microbial biomass nitrogen (N) and carbon (C) were determined before planting and about 4 weeks after emergence. Within each site, the effect of soil amendments on garlic yield depended on scape removal. Garlic yield in nonamended soil was lowest when scapes were not removed. The effect of scape removal tended to diminish when compost or fertilizer was applied. Overall yields were 35% higher in the sandy loam soil compared to the loamy sand soil. Drought stress occurred during bulbing at both locations. Higher yields in the sandy loam soil were likely due to its higher water-holding capacity. Soil amendments did not consistently affect microbial biomass N and C; however, the sandy loam soil had 2 to 6 times higher biomass N and 3 to 4 times higher biomass C than the loamy sand soil and reflected the higher organic matter content of the sandy loam.
Don Merhaut and Julie Newman
Four types of media [coir, 1 coir: 1 peat (by volume), peat, and sandy loam soil] were evaluated for their effects on plant growth and nitrate (NO – 3) leaching in the production of oriental lilies (Lilium L.) `Starfighter' and `Casa Blanca'. Twenty-five bulbs were planted in perforated plastic crates and placed on the ground in temperature-controlled greenhouses. The potential for NO – 3 leaching was determined by placing an ion-exchange resin (IER) bag under each crate at the beginning of the study. After plant harvest (14 to 16 weeks), resin bags were collected and analyzed for NO – 3 content. Plant tissues were dried, ground, and analyzed for N content. Results indicated that the use of coir and peat did not significantly influence plant growth (shoot dry weight) relative to the use of sandy loam soil; however, substrate type influenced the amount of NO – 3 leached through the media and N accumulation in the shoots for `Starfighter', but not `Casa Blanca'.
D.S. Glinski, H.A. Mills, K.J. Karnok and R.N. Carrow
Root growth of `Penncross' creeping bentgrass (Agrostis palustris Huds.) plugs sodded into a sandy loam soil and fertilized with five 1:1, 1:3, and 0:1) were evaluated. Root growth and root: shoot ratios were higher with as the predominant N form. Results from this study indicate should be the predominant N form when rapid and extensive root development is desired for the establishment of sodded bentgrass.
John Sloan* and Wayne Mackay
Soils exhibit a degree of hydrophobicity and can repel water rather than absorb it. Surfactants lower the surface tension of water which may increase its infiltration into the soil and adsorption to soil solids. The objective of this study was to determine if water treated with a surfactant would increase conserve soil moisture and decrease the amount of water needed to sustain healthy plant growth. Clay and sandy loam soils were placed in 15-cm greenhouse pots. Impatiens seedlings were transplanted into each pot. All pots were fertilized equally and the Impatiens flowers were allowed to grow for 8 weeks. Then the pots were treated with tap water or tap water mixed with a commercial surfactant at one times (1×) or two times (2×) the recommended rate. After applying the water treatments, pots received no additional water. Each pot was weighed twice per day and the plants were observed for signs of wilting. Upon initial signs of wilting, each plant was rated on a scale of 1 to 3 with 1 = no wilting, 2 = leaves starting to droop, and 3 = wilting leaves and stems. Addition of the surfactant at the 1× and 2× rates slowed the loss of water from both the sandy loam and the clay soils. The effects of the surfactant were apparent within 3 to 5 days in the sandy loam soil and 6 to 10 days in the clay soil. The benefits of reduced water loss from soil were manifested by reduced wilting in Impatiens plants in soils treated with 1× and 2× the recommended rate of surfactant. In the clay soil, use of the surfactant increased the amount of time before Impatiens plants began to wilt. It appears that adding a surfactant to irrigation water can conserve soil moisture and extend the time between water applications.
Salvadore J. Locascio, George J. Hochmuth, Fred M. Rhoads, Steve M. Olson, Alan G. Smajstrla and Ed A. Hanlon
Tomato (Lycopersicon esculentum Mill.) was grown with drip irrigation on an Arredondo fine sand and on an Orangeburg fine sandy loam to evaluate the effect of N and K time of application on petiole sap, leaf-N and -K concentrations, fruit yield, and to determine N and K sufficiency ranges in leaf tissue. On the sandy soil, N—K at 196-112 kg·ha-1 were applied 0%, 40%, or 100% preplant with the remainder applied in 6 or 12 equal or in variable applications in 12 weeks. With the variable application rate, most nutrients were applied between weeks 5 and 10 after transplanting. On the sandy loam soil that tested high in K, only N (196 kg·ha-1) was applied as above. Petiole sap K concentration declined during the season, but was not greatly affected by treatment. Petiole NO3-N concentrations decreased during the season from 1100 to 200 mg·L-1, and the decrease was greater with preplant N treatments. On the sandy soil, marketable fruit yields were lowest with 100% preplant, intermediate with 100% drip applied (no preplant N), and highest with 40% preplant and 60% drip applied. With 100% drip applied, yields were higher with 12 even applications than with either six even weekly applications or with 12 variable N and K applications. With 40% preplant, timing of application had little effect on yield. On the sandy loam soil in 1993, yields were highest with 100% preplant, intermediate with 40% preplant and 60% drip applied, and lowest with all N drip applied. In 1994 when excessive rains occurred, yields were similar with all preplant and with split N applications. Petiole N concentration was correlated with tomato yield, especially at 10 weeks after transplanting. The best correlation between sap-N and total yields occurred between 4 and 6 weeks at Gainesville and between 4 and 10 weeks at Quincy.
Gene E. Lester and Kevin M. Crosby
Two important chemicals and an essential mineral (phytonutrients) for human health and well-being are ascorbic acid, 5-methyl-tetrahydrofolic acid (folic acid) and potassium. The influence of cultivar, fruit size, soil type and year on these compounds in [Cucumis melo L. (Inodorous Group)] was determined. Fully mature (abscised) commercial size fruit: 4, 5, 6, 8, and 9 (fruit/0.031 m3 shipping box) from three commercial cultivars: Mega Brew, Morning Ice, and TAM Dew Improved (TDI); and one experimental hybrid `TDI' × `Green Ice' were grown on both clay loam and sandy loam soils. Total ascorbic acid and folic acid content increased with an increase in fruit size up to a maximum (size 6 or 5), then decreased with further fruit size increase. Total ascorbic acid and folic acid content for most fruit sizes were higher when grown on clay loam versus sandy loam soils. The experimental hybrid compared to the commercial cultivars contained generally higher total ascorbic acid levels and significantly higher folic acid levels regardless of fruit size or soil type. Free ascorbic acid and dehydroascorbic acid contents were generally higher from clay loam versus sandy loam soils and in the experimental line versus the commercial cultivars. However, free ascorbic acid content was high in small fruit and remained unchanged with an increase in fruit size until size 6 or 5 then significantly decreased; while dehydroascorbic acid content linearly increased with an increase in fruit size. Potassium content averaged 1.7 mg·g-1 fresh weight for each line and did not significantly differ due to fruit size, but did for soil type and year. Analyses of variance for the phytonutrients assayed demonstrated that cultivar (genetics) always was very highly significant (P = 0.001), whereas, soil and year (environment) were not.
John R. Clark and James N. Moore
The southern highbush blueberry cultivars `Blueridge', `Cape Fear', `Georgiagem' and `O'Neal' were evaluated for their response to sawdust/woodchip mulch for five years at Clarksville, Arkansas on a Linker fine sandy loam soil. Mulched plants produced higher yields and larger plant volumes than non-mulched. Berry weight was similar for mulch treatment except for the first fruiting year. All cultivars responded to mulch, although `Blueridge' and 'Cape Fear' produced the higher yields. General response of these cultivars of southern highbush was similar to that of northern highbush in previous mulch studies in Arkansas.
Adán Fimbres Fontes, Raúl Leonel Grijalva Contreras and Manuel de Jesus Valenzuela Ruiz
The area of olives in the region of Caborca has been increasing in the last years to 4500 ha. Olives in other regions do not need the application of water, at Caborca evaporation is greater than rainfall. Because of that situation, an experiment was conducted in 1998 to determine the optimum water requirements and the crop coefficient for `Manzanillo' olives (2 years of planted) under drip irrigation and microsprinkler in a sandy loam soil. The results indicated no difference between treatments (50%, 75%, and 100% of ET estimated in a pan evaporation). The water applied to each treatment was 13.32, 19.98, and 26.64 cm.
V. A. Khan, C. Stevens, J. Y. Lu, M. Kabwe and Z. Haung
Clear (CM) and black (BM) plastic mulch and bare soil (BS) plus VisPore (V) row cover (VCM, VBM, VBS), BM, CM and BS in combination with drip irrigation were used to evaluate the growth response of these treatment combinations on 5 and 9 wks old `Clemson Spineless' okra transplants grown in sandy loam soil. Mulched treatments significantly increased the survival rate of 5 wks old transplants while VCM and VBM treatments increased significantly the number of vegetative branches of 5 wks over 9 wks old transplants. Total and marketable yield, as well as total and marketable number of pods were significantly influenced by mulched treatments rather than by the age of transplants.