Preliminary investigations on the effects of no‐till corn production methods on specific soil mesofauna populations

Abstract

Moldboard plowing, chisel plowing and no‐till methods were used to produce field corn (Zea mays) in an old grass sod. Grain yields were similar ranging between 13,100 and 14,186 kg/ha. The greatest spread in soil temperatures was only 2.1 C with the plowed soil always being warmest. Mean soil organic matter levels of the surface soil ranged between 1.9 percent on the moldboard plowed plots and 3.3 on the no‐till plots. Ten species of soil Collembola were identified. Collembola and Acarina populations were concentrated in the surface 5 cm of soil and were present in greatest numbers in the No‐Till soil.     

The role of fertilization on phosphorus stratification in no‐till soils

Abstract

No‐tillage induces the stratification of soil nutrients because of the return of crop residues to soil surface, fertilization and the lack of soil mixing. In this research we have attempted to develop a phosphorus (P) balance on soybean, to study the relative importance of the causes of P stratification. An experiment was performed on a Typic Hapludoll located in mid Buenos Aires province, Argentina. The treatments were fertilized and unfertilized. Soybean biomass and P concentration in grains, stubble and roots were determined. In both treatments the P stratification was produced by the enrichment of the surface layer and the impoverishment of the deeper layers. In the non‐fertilized plots the soil lost P (7.5 kg P ha¹) meanwhile in the fertilized plots (20 kg P ha^‐1added) the soil gained P (6.6 kg P ha^‐1). The accumulation of plant residues alone is enough to redistribute P in soils, but fertilization was the main factor in P stratification.     

Measurement of available soil phosphorus under conventional and no‐till management

Abstract

The objective of the investigation was to compare the predominant forms of P in fields of an acid Matapeake soil under no‐till and conventional‐till management. The fields, which differed in extent of contact between soil and fertilizer P, also differ in forms of P. Fertilizer P remained in the uppermost layer of no‐till fields and was, therefore, not in as close proximity to the plant (corn) roots as P was in conventional‐till fields. Nevertheless, fertilizer P in the no‐till fields underwent only limited conversion to forms less available to plants and thus, in part, may have accounted for similar plant uptake rates of P in no‐till and conventional‐till fields.

One method used to analyze P in the Matapeake soil was the double‐acid‐extraction method. This method is used by several state soil‐testing laboratories of the eastern and southeastern United States, where acid soils like Matapeake are common. The double‐acid‐extraction method underestimated the soil P available for plant uptake.     

Release and recovery of nitrogen from winter annual cover crops in no‐till corn production

Abstract

Soil bulk density markedly influences hydrolysis of surface‐applied granular urea that is vulnerable to serious ammonia volatilization losses. In order to decrease the ammonia losses by retarding urea hydrolysis, several chemicals have been tested for their soil urease inhibition properties. Phenyl phosphorodiamidate (PPDA) is a potent soil urease inhibitor. Laboratory studies using soil column incubations were conducted to investigate the effect of soil bulk density on inhibition of hydrolysis of surface‐applied urea granules (=20 mg of urea/granule) containing 1% PPDA in unsaturated soils. The increase in soil bulk density (from 0.69 to 1.50 Mg/m³) markedly increased the rate of hydrolysis of surface‐applied urea granules and significantly decreased the apparent urease inhibition by PPDA present in the granules. These results are attributed to the probable spatial separation of urea and PPDA because of the differences in diffusive transports in unsaturated soils caused in part by differences in their solubilities in water.     

The effect of gamma‐radiation on the release of carbon dioxide from fresh soil

Abstract

The release of CO₂ from fresh soil at medium moisture was examined for 14 days after the application of gamma‐radiation over the range 0.025 ‐ 10 Mrad. All doses stimulated the release of CO₂ compared with non‐irradiated soil, but there was no extra yield of gas between 4 and 10 Mrad. Rapid evolution occurred during irradiation and over the next 24 hours, but towards the end of incubation both irradiated and untreated soil produced CO₂ at similar rates.

Studies to elucidate the origin of CO₂ indicated that the contribution from enzymes was predominant up to 2 Mrad, but at 10 Mrad, 45% of the gas could be formed by radiolytic decarboxylation of soil organic matter. Consequently, heavy irradiation of soil cannot stop production of CO₂, and if high concentrations do interfere with the application of radiation to specific soil research investigations, the gas should be displaced or allowed to diffuse from the sample.     

Variation of early growth and nutrient content of no‐till corn and soybean in relation to soil phosphorus and potassium supplies

Abstract

Knowledge of relationships between variation in early plant growth and soil nutrient supply is needed for effective site‐specific management of no‐till fields. This study assessed relationships between soil test phosphorus (STP) and potassium (STK) with early plant growth and P or K content of young corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] plants in eight no‐till fields. Composite soil (0–15 cm depth) and plant (V5‐V6 growth stages) samples were collected from 400‐m² areas at the center of 0.14‐ha cells of a 16‐cell square grid and from 2‐m² areas spaced 3 m along each of two 150‐m intersecting transects. Correlation, regression, multivariate factor analyses were used to study the relationships between the variables. Variability was higher for samples collected from the transects. Plant dry weight (DW), P uptake (PU), and K uptake (KU) usually were correlated with STP and STK but the correlations varied markedly among fields. Relationships between soil and plant variables could not always be explained by known nutrient sufficiency levels for grain production. Plant P concentration (PC) was not always correlated with STP and sometimes it increased linearly with STP, but other times increased curvilinearly until a maximum was reached. Plant K concentration (KC) usually was correlated with STK, however, and increased linearly with increasing STK even in fields with above‐optimum STK. The results suggest greater susceptibility of early growth to STP than to STK and greater plant capacity to accumulate K compared with P over a wide range of soil nutrient supplies. Variation in STK likely is a major direct cause of variation in KC over a wide range of conditions but variation in STP is not likely a major direct cause of variation in PC when high STP predominates.     

Sulfur nutrition of winter wheat varieties with till and no‐till planting on highly weathered alfisol soils

Abstract

Winter wheat (Triticum aestivum L.) occupies large hectarage and is important in crop rotations on the highly weathered, low organic matter silt loam soils common in southern Illinois and the southern midwest United States region. Sulfur (S) is an essential element with some potential for deficiency, but it is not commonly applied to winter wheat grown on these soils. This study was conducted to determine if S nutrition is limiting winter wheat growth and grain yield. Interactive effects of topdressed fertilizer S (0 and 28 kg S/ha), tillage (disk‐till, DT and no‐till, NT), and wheat variety on plant growth, nutrient concentration, and grain yield were investigated for three crop years on two soils in southern Illinois; Cisne silt loam (fine, montmorillonitic, mesic Mollic Albaqualf), Brownstown site, and Grantsburg silt loam (fine‐silty, mixed, mesic Typic Fragiudalf), Dixon Springs site. Grain yield was unaffected by S application although flag leaf and whole plant S concentrations increased. Lack of yield response to S application was consistent each year on both soils and across all varieties and tillage systems. Equivalent yields were produced with both tillage systems at Brownstown, but slightly lower yield occurred with no‐till at Dixon Springs. Plant S concentrations and soil sulfate levels indicated sufficient S was available from sources other than fertilizer S, including extractable soil S and atmospheric deposition. Wheat variety consistently influenced plant nutrient composition and grain yield more than tillage or application of S fertilizer. If, in the future, wheat grain production, atmospheric S deposition, and extractable soil S remain at levels measured in this study, then S fertilizer applications would not be expected to increase winter wheat grain yield.     

Origin of the effect of ph on the saturated hydraulic conductivity of non‐sodic soils

Abstract

The effect of pH on the saturated hydraulic conductivity (K) of repacked columns of two non‐sodic soils (Healaugh and Fagaga soils) was examined. The K value was greater for the Fagaga soil than for the Healaugh soil which is attributed to the difference in the amount of free iron oxides between the soils. The K values reached a maximum when the pH was close to the point of zero net charge (PZNC) (3.7 and 4.8 for the Healaugh and the Fagaga soil, respectively) and decreased on either side of these pH values. The effect of pH on K was related to its effect on surface charge. As the pH of variable‐charge soils approaches the PZNC, the net surface charge decreases resulting in flocculation and maintenance of a high K. Conversely, as the pH deviates from the PZNC, the net surface charge increases, resulting in dispersion and a decrease in K. There was a negative relationship between the amount of dispersed clay and the K values, suggesting that clay dispersion and the resulting clogging of pores decreases K in these soils.     

Yield of iron‐sprayed and non‐sprayed strawberry cultivars grown on high ph calcareous soil

Abstract

Iron (Fe) deficiency chlorosis (FeDC) results in extensive reduction in yield of strawberry (Fragaria x ananassa Duch.) grown on high pH calcareous soils. Three cultivars differing in response to FeDC were grown on a high pH (8.2) calcareous soil (25.4% calcium carbonate equivalent in surface 20 cm) in the field (Choueifat, coastal area of Lebanon) to determine the effects of FeDC on fruit yield of cultivars sprayed with FeEDDHA [ferric ethylene‐diiminobis (2‐hydroxyphenyl) acetate]. The unsprayed plots were used as a control. No significant interaction (P<0.05) between cultivars x FeEDDHA spray treatment, and no significant differences (P<0.05) between one and two FeEDDHA spray(s)/week treatment was noted for visual FeDC, fruit number, and fruit yield. Sprayed cultivars once a week produced higher yields than unsprayed ones; overall increases were 33% (13% for ‘Motto’, 30% for ‘Chandler’, and 56% for ‘Douglas'). Even though only slight FeDC was noted on the ‘Motto’ cultivar receiving no Fe EDDHA spray, fruit yields were increased when sprayed with FeEDDHA. However, significant increases in yield for ‘Chandler’ and ‘Douglas’ cultivars with severe FeDC ratings were rioted when sprayed with FeEDDHA.     

Effect of rock phosphate and superphosphate on crop yield and soil phosphorus test in long‐term fertility plots

Abstract

A long‐term (1968–1987) field study using corn‐soybean in rotation was conducted to compare the effect of rock phosphate (RP) and superphosphate (SP) at two lime levels on crop yield, soil available phosphorus (P) as Bray P‐1 (0.025M HCl + 0.03M NH₄F) and Bray P‐2 (0.1M HCl + 0.03M NH₄F) tests, and on the relationship between crop yield and available P tests. Treatments included a control, application of RP and SP ranging from 12 to 96 kg P₂O₅ ha^‐1 yr^‐1, and combinations of RP with SP or sulphur at various rates. The RP was applied once in 1968 at 8 times the annual rate while SP was applied annually until 1985. Corn and soybean yields increased with P application, more with SP than with RP. Bray P‐l and Bray P‐2 increased linearly with the amount of P applied as SP or RP. A significant correlation (r > 0.64) was found between corn yield and Bray P‐2 at low lime level with both P sources. In contrast, a poor correlation (r < 0.50) was found between soybean yield and soil P tests. Both RP and SP were effective sources of P fertilizers for corn on soils treated with a small amount of lime compared with a large amount of lime. Under low lime the Bray P‐2 accounted for 41% and 66% variability in com yield with applied RP and SP, respectively. On the other hand, Bray P‐1 was only of value when SP was the source of P.     

Effects of soil compaction and water‐filled pore space on soil microbial activity and N losses

Abstract

Soil compaction is a significant production problem for agriculture because of its negative impact on plant growth, which in many cases has been attributed to changes in soil N transformations. A laboratory experiment was conducted to study the effect of soil compaction and water‐filled pore space on soil microbial activity and N losses. A hydraulic soil compaction device was used to evenly compress a Norfolk loamy sand (fine‐loamy, siliceous, thermic Typic Kandiudults) soil into 50 mm diameter by 127 mm long cores. A factorial arrangement of three bulk density levels (1.4, 1.6, and 1.8 Mg/m³) and four water‐filled pore space levels (60, 65, 70, 75%) was used. Fertilizer application of 168 kg N/ha was made as 1.0 atom % ¹⁵N as NH₄NO₃. Soil cores were incubated at 25°C for 21 d. Microbial activity decreased with both increasing water‐filled pore space and soil bulk density as measured by CO₂‐C entrapment. Nitrogen loss increased with increasing bulk density from 92.8 to 334.4 g N/m³ soil at 60% water‐filled pore space, for 1.4 and 1.8 Mg/m³, respectively. These data indicate that N loss and soil microbial activity depends not only on the pore space occupied by water, but also on structure and size of soil pores which are altered by compaction.     

The effect of gypsum and other salts on the growth of narrow‐leafed lupins

Abstract

Glasshouse experiments were conducted to establish the cause of poor lupin growth in the presence of gypsum in field trials which had been conducted in Western Australia. In the first experiment, Bradyrhizobium‐inoculated lupins were grown in nutrient solutions with varying concentrations (1, 3, 5, and 10 mM) of calcium (Ca) and sulfate (SO₄) added as either CaSO₄, K₂SO₄, or CaCl₂ to establish whether gypsum caused Ca or SO₄ toxicity to the plants. Although a general decrease in lupin plant growth was observed as the concentration of each salt increased, there was no evidence that either Ca or SO₄ directly caused toxicity to the plants. Two soil experiments were therefore conducted to investigate lupin growth responses to the salts in a soil environment. The first soil experiment was conducted in a yellow earth— the same soil in which lupins had been adversely affected by gypsum in the field. The second soil experiment was conducted in the topsoil of a siliceous sand. Basal nutrients and different rates of CaSO₄, K₂SO₄, and CaCl₂ were added so that similar amounts of Ca and SO₄ were present for each treatment at a given application rate. In both soils, lupin growth generally decreased as the application rate of treatments increased, although the magnitude of the decrease in growth was higher in the yellow earth than the siliceous sand. The strongest correlation between lupin growth and a soil solution chemical property was a log‐linear relationship between the shoot or root dry weight and the electrical conductivity (EC) of the soil solution. Plant nutrition was affected by different treatments, particularly with respect to nutrient balances. It is suggested that a high ionic strength in the soil, which results when gypsum is applied in the field, may contribute to the lupin yield decline. Possible reasons for the effect are discussed.     

The effect of water and acid‐washing soil treatment on the measurement of pH,delta pH and zero point of charge in some variable charge soils

Abstract

This study was undertaken to determine the effect of previous water and acid‐washing soil treatment on soil pH, Delta pH and Zero Point of Charge of soil surface samples of three Hawaii soils, Molokai (Typic Torrox), Wahiawa (Tropeptic Eutrustox), and Hilo (Typic Hydrandept).

The acid‐washing treatment lowered the soil pH and shifted the Zero Point of Charge to lower pH values. The effect was greater in the Wahiawa and Molokai soils that are dominated by oxidic materials. Whereas the acid‐washing treatment did not change the magnitude of the negative charge in the Wahiawa and Molokai soils, it overestimated the magnitude of the positive charge in the Hilo soil. This phenomena probably was enhanced by the dominance of variable charge clay minerals in the Hilo soil. The results indicated that the acid‐washing treatment changed the nature of the charge characteristics of the soils, hence it should not be recommended in the characterization of the net charge in variable charge soils.     

Effect of extractable zinc,phosphorus, and soil ph on zinc concentrations in leaves of field‐grown corn

Abstract

The variability in corn yield responses to applications of Zn fertilizer appears to be associated with several complex soil and climatic factors that affect the availability of endogenous soil Zn to the crop under specific conditions. Among the soil chemical properties that influence availability of endogenous Zn are soil pH, organic matter content, and extractable P. Over a period of several years, soil and plant analysis data were collected from 54 field experiments, field trials, and diagnostic visits to producer's fields. These data were subjected to multiple regression analysis, resulting in an equation: Zn_leaf = 37.14 + 1.513 Zn_st ‐4.04 pH_st ‐ 1.791 ln(P_st/100) where Zn_st, pH_st, and P_st were 0.1N HC1 extractable soil Zn (kg/ha), 1:1 soil‐water pH, and Bray's 1 extractable soil P (kg/ha), respectively. These factors accounted for 67% of variation in leaf Zn, which was a large portion of the variability in Zn_leaf considering that climatic conditions, management levels, and varietal differences were uncontrolled in most instances. Using the previously published critical level in the leaf opposite and below the ear as 17 μg Zn/g, these data can be used to set required soil test levels of Zn at different levels of extractable P and soil pH. Inadequate levels of extractable Zn would range from 2.5 (at pH 6.0, P = 70 kg/ha) to, 9.5 kg/ha (at pH 7.5, P = 420 kg/ha).     

Twelve‐year tillage and crop rotation effects on yields and soil chemical properties in northeast Iowa

Abstract

Long‐term tillage and crop management studies may be useful for determining crop production practices that are conducive to securing a sustainable agriculture. Objectives of this field study were to evaluate the combined effects of crop rotation and tillage practices on yield and changes in soil chemical properties after 12 years of research on the Clyde‐Kenyon‐Floyd soil association in northeastern Iowa. Continuous corn (Zea mays L.) and a corn‐soybean [Glycine max L. (Herr.)] rotation were grown using moldboard plowing, chisel plowing, ridge‐tillage, or no‐tillage methods. Tillage and crop rotation effects on soil pH, Bray P1, 1M NH₄OAc exchangeable K, Ca, and Mg, total C, and total N in the top 200 mm were evaluated. Profile NO₃‐N concentrations were also measured in spring and autumn of 1988. Crop yields and N use efficiencies were used to assess sustainability. Bray P1 levels increased, but exchangeable K decreased for all cropping and tillage methods. Nutrient stratification was evident for no‐tillage and ridge‐tillage methods, while the moldboard plowing treatment had the most uniform soil test levels within the 200 mm management zone. Chisel plowing incorporated fertilizer to a depth of 100 mm. Soil pH was lower with continuous corn than with crop rotation because of greater and more frequent N applications. Profile NO₃‐N concentrations were significantly different for sampling depth and among tillage methods in spring 1988. In autumn the concentrations were significantly different for sampling depth and for a rotation by tillage interaction. Estimated N use efficiencies were 40 and 50 kg grain per kg N for continuous corn, and 48 and 69 kg grain per kg N for rotated corn in 1988 and 1989, respectively. The results suggest that P fertilizer rates can be reduced, but K rates should probably be increased to maintain soil‐test levels for this soil association. Crop rotation and reduced tillage methods such as ridge‐tillage or chisel plowing appear to meet the criteria for sustainable agriculture on these soils.     

The effect of sewage‐sludge on the heavy metal content of soils and plant tissue

Abstract

Domestic sewage sludge applied to farm fields at a rate of 44.9 kg/ha in a mixture with lime and sawdust was found to increase the soil levels of cadmium, chromium, copper, lead, mercury, nickel and zinc. The average levels in sludge treated soil were: 0.11, 0.56, 3.59, 2.72, 0.068, 1.49 and 2.57 ppm, respectively. The increases were small and the overall loading factors were well below recommended maximums. The uptake of these heavy metals by grass and legume plants was variable with cadmium, copper and zinc levels being higher in those plants growing in the sludge treated soils but only copper was significantly higher. The heavy metal contents found were all within the levels normally found in grass and legume plants. The higher mean concentration in plants growing on the sludge treated soils were cadmium 0.495; chromium 1.22; copper 12.3; lead 1.54; mercury 0.022; nickel 4.08 and zinc 28.4 ppm.     

Nitrogen response of no‐till corn in first and second years following conservation reserve program

Abstract

A considerable amount of land enrolled in the Conservation Reserve Program (CRP) has been and will be returned to row crop production. It is difficult to predict how to manage nitrogen (N) fertilizer for these row crops, since there are plausible reasons to expect either substantial N immobilization or substantial N mineralization due to the effects of CRP enrollment. Our objective was to characterize corn (Zea mays L.) yield response to N following CRP in order to develop N management recommendations. Corn was planted either directly into killed CRP sod (CRP‐corn) or following soybean [Glycine max (L.) Merr.] that had been planted into killed CRP sod (CRP‐SB‐corn)‐ We applied a range of N rates and determined the economically optimum N rate from the yield response data. In both years of the study, the optimum N rate for CRP‐corn was much higher (181 and 230 lb N acre^‐1 in 1996 and 1997, respectively) than theoptimum N rate for CRP‐SB‐corn(108 and 113 lb Nacre^‐1 in 1996 and 1997, respectively). CRP‐corn with no N fertilizer appeared extremely N deficient for the first half of the season. We observed a large flush of inorganic soil N in late summer of the first year out of CRP, but this N was apparently too late for optimum corn production that season. We recommend soybean as the first choice row crop to plant immediately following CRP. If corn is to be planted immediately following CRP, we recommend higher‐than‐normal N rates to optimize production.     

On‐farm monitoring of soil and crop nitrogen status by nitrate‐selective electrode

Abstract

Nitrate‐nitrogen concentration in fresh petiole sap, as measured by a portable, battery‐operated, nitrate‐selective electrode, was highly correlated with NO₃‐N concentration in dry petiole tissue of broccoli [Brassica oleracea L. (Italica group), r² = 0.84], celery [Apium graveolens L. var. dulce (Mill.) Pers., r² = 0.88], lettuce (Lacluca saliva L., r² = 0.77), pepper (Capsicum annuum var. annuum L., r² = 0.89), tomato (Lycopersicon esculentum Mill., r² = 0.83), and watermelon [Citrulius lanatus (Thunb.) Matsum. & Nakai, r² = 0.88]. This relationship was linear over a wide range of NO₃‐N values and was generally unaffected by site, crop, cultivar, or growth stage, provided that petiole tissue analyzed was from recently matured leaves. Sap was analyzed directly without dilution or filtration. The slope of the regression equation differed widely among crops. Selective electrode analysis of NO₃‐N concentration of soil solution samples obtained by suction lysimetry was also highly correlated with conventional laboratory technique (r² = 0.87). The nitrate‐selective electrode appeared to be a useful tool for on‐farm monitoring of soil and crop N status.     

Application of the Berthelot reaction to the determination of ammonium‐N in soil extracts and soil digests

Abstract

The phenol‐hypochlorite‐ammonium reaction of Berthelot can be utilized in manual procedures for the analysis of NH₄‐N in a variety of soils applications, including total N measurement in soils, particle size separates and soluble organic matter fractions, and in measuring NH₄‐N in soil extracts. A simple, convenient, and versatile procedure is described.