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Abstract: A laboratory incubation trial and a field litterbag study were conducted to determine the rate and magnitude of mineralization of dairy manure N components in a south central Wisconsin silt loam. Dairy manure components (urine, feces, or bedding, each 15N-labeled and the other components left unlabeled) were incubated in soil at 11, 18, or 25°C. Samples were taken at 14, 21, 42, 84, and 168 days and analyzed for mineralized N ($$\rm NH^{ + }_{4}$$ and $$\rm NO^{ - }_{3}$$) and 15N abundance in the inorganic and organic fraction (at day 168 only). In the field study, nylon mesh (38 μm) litterbags filled with 15N-labeled manure (2000) or unlabeled manure (2000 and 2002) were placed 7.5 cm below the surface and excavated at 7, 14, 21, 28, 35 (2000 only), 42, 56, 84, 98, and 126 days after burial and at corn (Zea mays L.) harvest, after 142 days in 2002 and 154 days in 2000. In the incubation study, 50−60% of applied urine N was mineralized showing the importance of this manure N component as a source of plant available N. About 14−19% of applied N was mineralized from the fecal and bedding components. In the litterbag experiment, approximately 70% of the dry mass and 67% of the N was mineralized from the litterbags with similar amounts measured using either labeled or unlabeled N. Rates of manure organic matter decomposition and N mineralization were best predicted using single exponential models for both years with most of the release occurring during the first 21 days.

Diagnostic indicators were developed to evaluate water storage, infiltration, drainage, and uptake distribution patterns over a potato (Solanum tuberosumL.) hill to improve efficiency in drip and sprinkler irrigation. Soil water content time series were measured in the hills and in the furrow between hills using time domain reflectometry. The drainage indicator was significantly (P= 0.05) higher under sprinkler than drip beneath the furrow and at the toe location. Storage was low at the center under sprinkler irrigation (0.05 m3m−3) where irrigation water did not infiltrate. Water storage was low at the shoulder location under both irrigation systems (significantly greater for sprinkler than drip) where high uptake rates were indicated. A diurnal/sinusoidal model of water uptake was fitted to a composite of the daily cycle of low-amplitude fluctuations with acceptable results (R2= 0.39-0.72) for both systems at the shoulder and toe locations and at the center under drip. Uptake was virtually undetectable (R2= 0.12-0.18) at the base and furrow locations. Deviations from the sinusoidal model were better accounted for by a polynomial model (R2= 0.29-0.83) and seemed to indicate irrigation-induced flow and nonsinusoidal uptake. Electronic noise also contributed to the variability. The indicator of peak uptake time shifted from about 3 p.m. to 8 p.m., and uptake decreased as the depth from the top of the hill increased. Management practices targeted at wetting the hill center under the sprinkler would likely improve water use efficiency under these conditions.

Measurements of dairy manure nutrient availability to crops typically show great variability. Approaches that are more accurate are needed to improve manure management and reduce nutrient loss to the environment. In this study, we compared direct (15N recovery) and indirect (difference method [Diff Meth] and fertilizer equivalence [FE] approach) methods of determining first‐year dairy manure N availability or recovery during three cropping seasons. A field experiment was conducted on a Plano silt loam (fine‐silty, mixed, superactive, mesic Typic Argiudolls) planted to corn (Zea maysL.). Plots received either manure, fertilizer N, or no N. Microplots receiving 15N‐labeled manure were also established each study year. Manure was applied to a new plot each cropping season. Whole‐plant N uptake was the best crop parameter to use for FE estimates. Estimates of N availability by relative effectiveness (Rel Eff), which are derived from the Diff Meth, and FE were similar (32 and 41%, respectively) and higher than unlabeled N or 15N recovery measurements because these indices factor in N use efficiency. Measures of the Rel Eff of manure N use were highly affected by control plot N uptake. The FE approach is less influenced by control plots, but it requires the inclusion of several more treatments and use of mathematical functions to describe crop response to N. These limitations are reflected in the wide ranges obtained for N availability estimates (−60 to 148%). Although apparent N recovery by the Diff Meth (14%) or direct measurements of 15N recovery (16%) were close on average, variability tended to be much lower for the 15N method. In addition, the Diff Meth was highly dependent on initial soil conditions. Use of 15N‐labeled manure, although more costly and time‐consuming, provided more consistent and reliable results.

Infiltration runoff measurements were made on nine urban lawns using a sprinkling infiltrometer in conjunction with the application of a complete fertilizer at three rates. The amounts of inorganic N, P, and K removed with the runoff water were determined. Results of the infiltration measurements show that the presence of textural and compaction discontinuities within the soil profile, formed during building and lawn construction, was probably the greatest factor affecting infiltration. Where these discontinuities were distinct, water intake was reduced to about 35% of that for a lawn with an undisturbed profile. For lawns with similar infiltration characteristics, a first order relationship appeared to exist between amounts of fertilizer applied and amounts lost. A second order equation, however, best described the relationship between percent of applied fertilizer in the runoff and 90‐min cumulative infiltration. When the simulated storm was applied immediately after fertilizer application, fertilizer losses averaged 10.6%; however, when fertilizer application was followed by recommended watering before the intense storm, average losses were reduced to 1.7% of the amount applied.

The effect of soil applications of WEX, Basic H, and Amway Spray Adjuvant was evaluated using corn (Zea maysL.), soybean [Glycine max(L.) Merr.], or potato (Solanum tuberosumL.) as test crops at three Wisconsin locations. Each wetting agent is a nonionic surfactant, and claims or has claimed to improve crop yield, quality, and nutrient availability. WEX was evaluated at recommended fertilization levels. Amway and Basic H, in the corn experiments, were evaluated at varying levels of applied N. Basic H was evaluated on potatoes at 30, 50, and 100% of the entire recommended fertilization program. Although crop yield was increased by fertilization in all cases, no yield improvements were observed from the use of any wetting agent at any fertilizer rate. No differences in nutrient availability as evidenced by foliar nutrient content of N, P, and K or crop protein levels were observed in association with the application of a wetting agent.

Calcitic papermill lime‐sludge, a by‐product of the kraft paper process, was evaluated as a liming material and its equivalency with dolomitic agricultural limestone determined. An incubation study involving 10 medium‐ or light‐textured Wisconsin soils demonstrated that lime‐sludge neutralizes soil acidity very rapidly. Maximum soil pH was achieved in less than 1 week after application of the lime‐sludge, while the pH of soils treated with finely‐ground agricultural limestone increased continuously throughout the 24‐week incubation period. In field trials conducted for 3 years on two different soils, corn (Zea maysL.) was followed by alfalfa (Medicago sativaL.) or birdsfoot trefoil (Lotus corniculatusL.). Both legumes responded favorably to liming but not differently to the lime‐sludge and agricultural limestone, whereas a response was not observed for corn. Yield data provided no evidence that use of the calcitic lime‐sludge created Mg stress in any tested crop. Plant tissue analyses and the absence of a yield response to soil‐applied MgSO4•7H2O supported this observation. The liming equivalency of lime‐sludge to agricultural limestone was examined under both laboratory and field conditions. Both suggested that 1 m3of the lime‐sludge has the same liming value as 1.1 metric tons of agricultural limestone with a neutralizing index of 60 to 69. This value is considerably less than the equivalency of 1.5 yd.3of lime‐sludge per ton of 60 to 69 agricultural limestone specified by Wisconsin Administrative Code.

Estimates of N, P, and K availability to corn (Zea maysL.) from injected dairy manure on three field sites in south central Wisconsin were made using a fertilizer equivalence approach. Nutrient uptake from treatments of a control, three rates of manure (approx. 53, 97, and 138 Mg ha−1yr−1on a wet basis), and three rates of broadcast fertilizer were evaluated. Crop nutrient recoveries of fertilizer N, P, and K were generally higher than crop recoveries of manure total N, P, and K. Estimates of first year N, P, and K availability showed substantial variability across rate, location, and year with standard deviations often about 50% of the mean. Ranges for N, P, or K availability were 12 to 63, 12 to 89, and 24 to 153%, respectively. These data do not identify those factors responsible for differences in nutrient availability from one site‐year to another. Biological or chemical availability indices of a 1‐wk anaerobic incubation at 40 °C or a 16‐h autoclaving in 0.01 MCaCl2solution were evaluated as measures of N availability and compared with field results. Correlations between measured changes in NH4‐N from these indices, as well as total Kjeldahl N and inorganic N levels in the top 30 cm of soil 4 to 6 wk after treatment application, and N uptake indicated inorganic N levels to be a better index of N availability than the other indices examined. However, to determine nutrient availability on a routine basis, more reliable biological or chemical indices are necessary. A simple model may help to simulate environmental effects and the contribution of residual nutrients in the soil.

Calcium applications to low Ca, sandy soils can improve potato (Solanum tuberosumL.) grade and USlA size grade, and these improvements are significantly correlated with increased periderm Ca concentrations. This study evaluated the effectiveness of several Ca sources (pelleted CaSO4, granulated CaSO4, sieved CaSO4, dolomitic lime, triple superphosphate, or CaCl2), methods of application (broadcast, sidedress, and preplant strip), and rates (84–336 kg Ca ha−1) on increasing tuber Ca on two irrigated loamy sands (Typic Udipsamments) in Wisconsin from 1983 to 1985. The addition of Ca increased the percent of grade USlA tubers, the yield of prime size (<170–370 g) USlA tubers, and periderm Ca concentrations. It also reduced the percent of USlB or cull tubers, the yield of small (170 g) USlA tubers, and the concentration of periderm Mg. Improvements of grade USlA tubers ranged from 3 to l0%, and yield of USlA prime tubers was increased from 2 to 10 Mg ha−1. Dolomitic lime, triple superphosphate, and CaCl2did not consistently improve tuber yield or grade, whereas CaSO4in any of the forms applied was an effective Ca source. In 1985, a vertical cross‐section of the potato hill was sampled to determine the distribution of exchangeable Ca in the hill for each application method. The accumulation and uptake of Ca in the plant tops and in tuber periderm and medullar tissue for an untreated control and each application method were determined at several times during the season. The preplant strip method concentrated more material in the central portion of the potato hill where the tubers formed, and increased Ca uptake in both periderm and medullar tissue compared to the sidedress and broadcast treatments. Calcium concentration and uptake in the plant tops was not affected by any method of Ca application. Total Ca uptake averaged 8.5 and 32.9 kg Ca ha−1in the tuber and plant tops, respectively.

A field experiment was conducted on a Piano silt loam (Typic Argiudoll) in southcentral Wisconsin to monitor N transformations following liquid manure injections. Liquid manure with and without a nitrification inhibitor [nitrapyrin, 2‐chloro‐6‐(trichloromethyl)pyridine, 13 mg a.i. L−1liquid manure] was injected into an uncropped area in June 1985. Soil samples were taken using a grid placed over the vertical cross‐section of the injected bands permitting spatial sampling in the vertical plane. Sampling was done 5, 12, 26, 39, 67, 99, and 350 d after manure application by progressive exposure of the band. Soil water content, pH, NH4‐N, (NO2+ NO3)‐N, Cl, and water‐soluble C were determined. The synagraphic computer program, SYMAP, was used to evaluate spatial changes in inorganic N concentrations in the manure injection zone. Nitrapyrin was not effective in inhibiting nitrification at the rate used. Nitrification occurred at the outer fringes of the band within 5 d; maximum concentrations of 300 to 800 mg NO3‐N kg−1occurred throughout the injection zone at 26 d. High respiratory activity in the injection zone was indicated by an almost threefold decrease in water‐soluble C between day 5 (750 mg C kg−1) and day 12 (270 mg C kg−1). Water content remained higher than the surrounding soil in the injection zone for 99 d. Once NO3leaching occurred, NO3‐N/Cl ratios decreased with depth under the injection zone. The abundant supply of NO3and readily oxidizable C, combined with the high moisture environment, led to the conclusion that liquid manure injections created an environment conducive for denitrification.

Abstract: Field experiments were conducted over eleven site-years where five K rates (0, 93, 187, 280, and 373 kg K ha−1) as KC1 or K2SO4 were band-applied at planting to potato (Solanum tuberosum L. ). Significant yield increases up to 332 kg K ha−1 were observed in five of eleven site-years when soil test K ranged from 75 to 110 mg kg1. The increase in tuber yield was associated with an increase of tuber size (170 to 370 g) and above in the US#1A category. Lack of yield response at the other site-years may be due to the high soil test K (125 to 180 mg kg−1). Statistically significant differences in total tuber yield were not evident between the two sources of K fertilizer studied; however, there was a tendency for a significant rate x source interaction (p > 0.15) in five site-years where K2SO4 increased tuber yield more than KC1 at rates up to 280 kg K ha−1. Above this rate, tuber yield decreased for K2SO4 but remained stable for KC1. Based on the tuber yield data and initial soil test K from the controls of each site-year, data from this study suggest that 104 mg K kg−1 is a critical pre-plant soil test level. A reduction in specific gravity with increasing applied K was evident in most of the site-years of this study, although decreases were generally not as marked when K2SO4 was used. A significant decrease in hollow heart with increasing rate of K fertilization was observed in four of eleven site-years; however, statistically significant yield responses to added K were found at only one of these sites. The incidence ofRhizoctonia solani was generally not affected by K rate; however, there was a tendency in some site-years for a higher disease incidence when KC1 was used instead of K2SO4 Potassium rate slightly decreased stem numbers per seed piece, averaging 3.7, 3.6, 3.5, 3.4, and 3.3 across all experiments, for the 0, 93, 187, 280, and 373 kg K ha−1 rates, respectively.

Injection of liquid organic wastes into soil promotes conditions that may be conducive to denitrification by creating an anaerobic environment abundant in inorganic N and readily oxidizable C. To quantify gaseous N loss, we measured N2O emissions from simulated waste injections applied to soils in large wooden containers (71 by 42 by 44 cm). These containers were equipped with headspace covers for gas entrapment, soil‐atmosphere wells, C2H2‐dispersion tubes, soil moisture‐temperature cells, and end‐entry doors for soil sampling. Soil type was a Plano silt loam (fine‐silty, mixed, mesic Typic Argiudoll) packed to a bulk density of 1.1 Mg m−3and maintained at a constant temperature of 12.0 ± 1.4 °C. Liquid dairy manure was injected into the soil at rates commonly used for crop production (79 000 L ha−1). The nitrification inhibitor nitrapyrin [2‐chloro‐6‐(trichloromethyl) pyridine] was used to further evaluate nitrification‐denitrification losses. Nitrous oxide emissions, with and without C2H2treatment, were estimated by passing air across the soil surface above an injection zone and trapping emitted N2O onto a molecular sieve. The largest emission of N2O occurred shortly after injection, followed by a shift to N2. Maximum gaseous‐N loss occurred 5 d after injection and corresponded with maximum CO2concentrations in the soil atmosphere. Nitrapyrin was effective in controlling nitrification, but did not consistently influence the rate of denitrification. When we simulated 190 mm of precipitation at 25 d after injection, increases in N2O production were minimal, possibly due to a limitation in readily oxidizable C. Total measured gaseous‐N loss in the presence of C2H2over 40 d accounted for 2.5 to 3.2% of the slurry's NH4‐N, or 1.0 to 1.3% of the total N added.

Potato tubers from field plots of calcium experiments in 1983 and 1984 were examined for the presence of internal brown spot. Presence of sub-apical necrosis on sprouts was also determined after storage in both years. Peel calcium concentration of 1983 tubers ranged from 0.226% to 0.130%; the range in percentage of these tubers with internal brown spot after 7 months storage was from 5.0% to 42.5%. The incidence of internal brown spot as well as sub-apical necrosis of sprouts was negatively correlated with tuber peel calcium levels (r = −0.754 and r = −0.792, respectively). Peel calcium concentration of 1984 tubers ranged from 0.224% to 0.104%; as in 1983, tuber calcium concentration was negatively correlated with the incidence of internal brown spot and sub-apical necrosis. Sub-apical necrosis of sprouts was present on 86.3% of the 1984 tubers with internal brown spot, and 65.3% of tubers with sub-apical necrosis on sprouts showed internal brown spot symptoms. The presence of sub-apical necrosis on tuber sprouts may serve as an indirect indicator of low calcium concentration in tubers.

Abstract: On low cation exchange capacity, sandy soils where soil test Ca is low, potato tuber (Solanum tuberosum L.) Ca levels may not be optimal for maximum yield or quality; therefore, this study evaluated the effect of several levels of applied Ca on potato yield and quality on four soil types in Wisconsin. Calcium was applied to a Plainfield loamy sand, a Keiner loamy sand, a Pence sandy loam, and an Antigo silt loam at five rates in 1984 (0, 84, 252, 420, and 588 kg Ca ha−1) and at six rates in 1985 (0, 56, 112, 168, 224, and 336 kg Ca ha−1) as a band of CaSO4 in the hill. In 1984, on the Plainfield soil, three rates of sidedress Ca(NO3)2 (0, 84, and 168 kg Ca ha−1) were factorially combined with the five CaSO4 treatments to evaluate the efficacy of Ca(NO3)2 as a concomitant Ca and N source. In general, total yield was not affected by CaSO4 additions; however, the addition of approximately 100 kg Ca ha−1 as Ca(NO3)2 increased total yield 3.6 Mg ha−1. On the low-CEC, low-Ca soils (Plainfield and Kelner), improved tuber grade and/ or US1A size grade were detected with the addition of up to approximately 300 kg Ca ha−1 as CaSO4. The percent of US1A tubers increased 5 to 10% and the yield of US1A prime size (170–370 g) tubers increased 3.4 to 8.4 Mg ha−1 above control values. These improvements were accompanied by increased periderm Ca concentrations, even though leaflet Ca concentrations were not affected by Ca applications. The use of 100 kg Ca ha−1 asCa(NO3)2 in combination with CaSO4 was more effective than CaSO4 alone. On higher soil test Ca soils (Pence and Antigo), responses were inconsistent and periderm Ca was generally not increased.

Corn (Zea maysL.) and potato (Solanum tuberosumL., ‘Russet Burbank’) were grown with and without the addition of the soil additive Symbex at different levels of fertilization. Symbex is marketed as a microbial soil inoculant claiming to accelerate decomposition of crop residue and N fixation. The efficacy of Symbex on the yield and quality of the two crops was evaluated at two sites for corn and one site for potato on a Typic Argiudoll, a Typic Hapludalf, and Typic Udipsamment, respectively, each for 3 years. Rates of fertilizer were 0, 20, 104, and 188 kg ha−1total N applied in the corn studies and 30, 50, and 100% of 756 kg ha−15‐10‐30 starter plus 224 kg ha−1of supplemental N in the potato study. Although both corn and potato yields were increased by fertilization, the use of Symbex did not affect the yield of either crop at any fertilizer rate. Foliar nutrient content of N, P, and K when compared by a paired t test over all fertility levels showed no differences associated with Symbex treatment by either crop. Symbex increased the rate of emergence of potato at all levels of fertility. A trend toward decreased size of grade US1A tubers was observed where Symbex was used.

The influence of P, K, and S on symbiotic fixation of N2in alfalfa nodules under field conditions is not well documented, even though through this mechanism shoot yield may be limited. The objective of this experiment was to study the effect of P, K, and S fertilization on alfalfa shoot yield, nodule numbers, and N2‐fixation as estimated by acetylene reduction by taking core samples (80 mm diam) at two sampling times at two locations (a silt loam and a loamy sand soil). Potassium fertilization increased shoot weight per plant, nodule number per core, and N2‐fixation rate at both locations more than the other nutrients studied. Shoot weight per plant increased 166% on the silt loam soil and 178% on the sandy soil with the addition of 448 kg K ha−1. Phosphorus fertilization also increased shoot weight at both sites but less than did K fertilization. Addition of P and S increased nodule numbers on the sandy soil but not on the silt loam soil. Nitrogen‐fixation rate was increased by 2.8 fold with the addition of 224 kg K ha−1on the sandy soil and 1.7 fold on the silt loam soil. Increased N2‐fixation resulted from K fertilization only when P was added to the silt loam soil. Phosphorus addition increased nodule numbers and N2‐fixation only on the sandy soil. The presence of a K ✕ S interaction for N2‐fixation but not for shoot weight or nodule number per core indicates that some differences in fertility response exist between N2‐fixation and other variables, even though all tend to be positively correlated. Sulfur fertilization had no effect on shoot weight but increased nodule numbers in alfalfa grown on sandy soil.

Anaerobically digested liquid sewage sludge was applied to field plots at rates of 0, 3.75, 7.5, 15, 30, and 60 metric tons dry solids/ha on a Warsaw sandy loam and a Piano silt loam during the summer of 1971. Additional experiments were established at both locations in 1972 and 1973 using the same treatment rates. Following sludge application the 1971 and 1972 trials were planted to rye (Secale cerealeL.). After rye forage harvest the following spring, the residual crop responses were tested with corn (Zea maysL.) on the 1971 and 1972 experimental areas for up to 3 years. The 1973 plots were initially cropped to sorghum‐sudan (Sorghum bicolorL. Moench × S. sudaneseP. Stapf.) followed by 1 year of corn. Yields of the first crop following sludge application typically increased significantly up to the 7.5‐metric ton/ha rate on the silt loam soil, and up to the 15‐metric tons/ha rate on the sandy loam soil. This corresponded to an application of 190 and 380 kg/ha of available N, and 183 and 366 kg/ha of total P for the 7.5 and 15 metric tons/ha rates, respectively. In some cases, the 30‐ and 60‐metric tons/ha rates depressed the first crop yields, possibly because of large amounts of soluble salts in the sludge. Residual benefits from sludge were evident for at least 3 years at the higher treatment rates. Increasing rates of sludge generally resulted in marked increases in the concentration of N and P in plant tissue. Total recovery by up to four successive crops averaged about 50% for available N and 7% for P at the low treatment rate, and about 14% for N and 3% for P at the highest treatment rate.

Liquid digested sewage sludge applied at rates from 3.75 to 60 metric ton/ha significantly increased the concentrations of inorganic N, organic N, and Bray P1extractable P in a sandy loam and a silt loam soil in south‐central Wisconsin. Most of the applied inorganic N was as NH4‐N and was nitrified rapidly. At sludge rates of 30 metric ton/ha or more, substantial losses of sludge‐applied N occurred by leaching. Soil solution NO3‐N concentrations exceeded 100 mg/liter at the 120‐ to 150‐cm depth 10 weeks after the first sludge application on the permeable sandy loam, and after about 1 year on the silt loam. The N balance indicated that considerable amounts of N may have been lost by denitrification, volatilization, or both, where > 30 metric ton/ha were applied. Mineralization of organic N was more rapid than previously reported. Up to 50% of the applied organic N was mineralized within 3 weeks after the last sludge application. During the remaining 25 months of the experiment, the mineralization rate was essentially constant at about 250 mg organic N/kg of soil/year at the 60 metric ton/ha sludge rate, and 180 mg organic N/kg of soil/year at the 30 metric ton/ha rate. Sludge applications resulted in immediate marked increases in Bray P1extractable P. However, the extractable P levels decreased with time after sludge application, probably as a result of P fixation. Significant amounts of P remained available for at least 2 years at the higher treatment rates.

Metal concentrations in soil and plant tissue resulting from land application of liquid digested sewage sludge were examined by determining Cu, Zn, Cd, Ni, and Cr in rye (Secale cerealeL.) and sorghum‐sudan (Sorghum bicolorL. Moench × S. sudaneseP. Stapf.) forage tissue, in corn (Zea maysL.) grain and stover, and DTPA‐extractable metals in soil. Four crops were grown successively after the application of up to 60 metric ton/ha (dry solids basis) of liquid sewage sludge on a sandy loam and a silt loam in Wisconsin. In general, the addition of sludge increased the concentrations of Cu, Zn, Cd, and Ni in the vegetative tissue but, except for Zn, the additions had relatively little effect on the metal content of corn grain. Chromium did not accumulate in the tissue or grain. In all cases, concentrations of metals were below levels considered to be toxic to the crops grown. Total recovery of added metals by the four crops was < 1% for Cu, Cd, Ni, and Cr, and 1 to 3% for Zn. Levels of DTPA‐extractable Cu, Zn, Cd, and Ni, but not Cr, increased with sludge treatment. Regression analysis showed that DTPA might be useful as a predictor of metal concentrations in the vegetative portions of the plant. However, the relationships were not the same for different crops. The decreases in metal concentrations in the plant tissue and in DTPA extracts with successive crops indicated reversion to less available forms for Zn, Cd, and possibly Ni. The ratio of Cd:Zn in the tissue was about one‐third that of the sludge for all crops.