Monocropped Corn Research Articles

Dynamics of soil fungal and bacterial biomass in a temperate climate alley cropping system

Soil bacterial and fungal dynamics were measured in an alley cropping system using direct microscopy techniques. The alley cropping system involved hedgerows of alder trees ( Alnus rubra) and sweet corn ( Zea mays) grown in the alleys. Trees were periodically coppiced and prunings were incorporated into the soil as green manure. Active fungal and bacterial biomass were greatest in tree rows and declined with distance from the trees. Active fungal biomass was greatest at the first year July sampling, ranging from 44 μg g dry soil −1 in the tree row to 22 μg g dry soil −1 in the middle of the alley. Bacterial biomass in all sampling locations peaked during May before coppicing of trees and cultivation of the alley. Bacterial and fungal biomass in the middle of the alley were similar to sweet corn monocropping plots throughout the growing season. The results suggested that the relatively low pruning biomass that can be produced and incorporated into the soil of temperate climate alley cropping systems compared to tropical alley cropping systems has little effect on microbial biomass. However, additional green manure in the form of leaf fall, additional below ground substrate from tree roots, and favorable conditions in untilled tree rows contribute to higher soil fungal and bacterial counts in and near the tree rows.

Intercropping corn with soybean, lupin and forages: weed control by intercrops combined with interrow cultivation

Intercropping corn with legumes is an alternative to corn monocropping and is a possible way to reduce the use of inputs, such as herbicides, while maintaining current weed control levels. Two experiments were carried out at each of two sites in both 1993 and 1994. The first experiment investigated the effects of seeding soybean or lupin alone or in combination with one of three forages (annual ryegrass, Lolium multiflorum Lam.; perennial ryegrass, Lolium perenne L.; and red clover, Trifolium pratense L.) on weed control. The second experiment examined the effects of seeding date (simultaneous with corn or 3 weeks later) and number of rows of large-seeded legumes (one or two) seeded between the corn rows, on weed control. Whenever seeding of legumes/forages was delayed, weekly interrow tillage operations were used to control weeds until legume/forage seeding. The density and biomasses of monocot weeds, either on or between the corn rows, were not affected by cultivation or intercropping. The density and biomass of dicot weeds on corn rows were reduced by some intercrop systems. For the various cropping systems tested, the dicot weed biomass and density between corn rows were most affected (in some cases reduced by 73–100% of the weedy control). A more effective dicot weed control was observed in delay seeded treatments, which allowed extra interrow cultivations. Intercrops that included soybean were also more successful at reducing weed populations than those containing lupin. Underseeded forages did not reduce weed biomass or density.

Confined Microplot Size for Nitrogen‐15 Uptake by Corn Plants in a Corn Intercrop System

AbstractThe high cost of labeled N fertilizer places practical limitations on measuring the fate of applied N. Applying of the labeled 15N to a microplot within a larger plot can reduce the cost. The objective of this study was to assess microplot dimensions required to produce reliable 15N data and cropping system effects on corn 15N uptake under a regime of monocropped corn (Zea mays L.) and corn intercropped with annual Italian ryegrass (Lolium multiflorum Lam.). Nitrogen was applied to large plots (15 by 75 m) at 270 kg N ha−1 on a fine, silty, mixed, nonacid, frigid Typic Humaquept soil during the 1993 and 1994 growing seasons. Enriched N fertilizer was applied to 1.15 by 1‐m2 confined microplots located in opposite halves of the large plot in each year of the study. Corn plants inside the confined microplots were sampled at 0.1, 0.3, and 0.5 m from the end borders of each microplot. In 1993, monocropping resulted in increases in leaf, stalk, and total dry matter production of 22, 41, and 30%, respectively, within microplots and relative to intercropped corn. There were no cropping system effects for these parameters in 1994. Monocropping increased atom % 15N enrichment in corn grain and stalks and increased fertilizer N recovery in all plant tissue compared with intercropping in both years. There were no differences in atom % 15N enrichment and fertilizer N recovery for plants harvested at the three sampling positions. These results suggest that a confined microplot with an area as small as 0.4 by 1.15 m can provide a reliable measure of fertilizer N recovery for corn plants in monocrop or intercrop systems. Any or all of the five plants within the microplot could be used to supply a reliable estimation of 15N recovery by corn plants.

Biomass Production and Nitrogen Uptake in Corn‐Ryegrass Systems

AbstractCropping systems, plant growth stages, and applied N fertilizer rates all directly affect N uptake. A 2‐yr study was conducted to evaluate the effects of cropping system [monocrop corn (Zea mays L.) and corn intercropped with annual ryegrass (Lolium multiflorum Lam.)] on dry matter (DM) production and distribution and on N uptake and allocation in the plants during the development of corn. Each of these corn systems was produced on a fine sandy loam (Typic Humaquept), using an application of 270 kg N ha−1 in each spring. Zero N (control) and conventional N rate (180 kg N ha−1) treatments were included for monocropped corn with conventional drainage. Plant tissues of all treatments were sampled at six‐leaf, tasseling, and mid‐grain filling stages, and after physiological maturity. In both years, DM production and N uptake of intercropped corn were lower than, or not different from, the monocropped corn (depending on growth stage). The total N uptake and DM production of the intercropping system (corn + ryegrass + weeds) were greater than those of the monocrop system. Application of 270 kg N ha−1 resulted in 20% less N recovery than 180 kg N ha−1 with monocropped corn production using free drainage. Both the corn‐ryegrass intercropping system and applied N rates altered the allocation of DM and N among different parts of the corn plants. The ryegrass and weeds were not able to take up enough of the extra N after the high N rate was applied for two consecutive years. The effect of precipitation on annual ryegrass growth was an important factor in N uptake by the intercropping system.

Nitrogen requirements of corn (Zea mays L.) as affected by monocropping and intercropping with Alfalfa (Medicago sativa)

Intercropping perennials with corn has the potential to improve utilization of the growing season over monocropping corn in regions where a substantial portion of the growing season is too cool for corn growth. The biomass potential and fertilizer N requirements of monocropped corn (Zea mays) grown using conventional tillage were compared with those of corn intercropped with alfalfa (Medicago sativa) in 1987 and 1988. The intercropped alfalfa was harvested once prior to planting the corn each spring. Rotation effects on and N fertilizer requirements for monocropped corn following these treatments and also following monocropped alfalfa, were evaluated in 1989 and 1990. During the two years of intercropping for which data is presented, the critical intercropped corn biomass (13.05 Mg ha−1) estimated using a quadratic-plus plateau model, was close to the monocropped corn biomass (13.01 Mg ha−1), but an estimated 83 kg ha−1 more N was required for intercropped corn to reach the critical biomass. Total biomass (intercropped corn and alfalfa) was 25% greater than that of the monocropped corn, and the total N uptake was 55% greater than that by monocropped corn over the two- year period. After rotation to monocropped corn using conventional tillage in 1989, corn biomass averaged over N rates following intercropping or monocropped corn was lower (P=0.01) than following monocropped alfalfa. Critical corn biomass estimated was highest following alfalfa and lowest following monocropped corn, and more N fertilizer was required to attain the critical biomass under continuous monocropped corn in 1989. Corn yields and N uptake values in 1990 were not significantly different among the cropping systems. The N fertilizer replacement values due to intercropping decreased from above 90 kg N ha−1 in the first year of rotation to less than 40 kg N ha−1 in the second year of rotation. Considering the higher potential for total biomass production and rotation benefit, intercropping is a viable alternative to conventional corn monoculture for forage production.

Net Returns from Eight Irrigated Cropping Systems on Clay Soil

Considerable research has been conducted on the agronomic relationships of cropping systems adapted to the clay soils of the lower Mississippi River floodplain (30°-37° North latitude); however, only a few studies included the determination and evaluation of net returns. An 8-yr study (1984-1991) was conducted on a Tunica clay (clayey over loamy, montmorillonitic, nonacid, thermic Vertic Haplaquept) to determine net returns above specified costs from eight nonirrigated cropping systems. The cropping systems included 1) monocrop corn (Zea mays L.) ; 2) monocrop soybean [Glycine max (L.) Merr.] ; 3) monocrop grain sorghum [Sorghum bicolor (L.) Moench.] ; 4) biennial rotation of corn and soybean ; 5) biennial rotation of grain sorghum and soybean ; 6) continuous wheat (Triticum aestivum L.)-soybean doublecrop ; 7) biennial rotation of corn and wheat-sobyean doublecrop ; and 8) biennial rotation of grain sorghum and wheat-soybean doublecrop. Cropping systems that included grain sorghum as a component produced the highest average net returns. Average net returns per acre from grain sorghum-soybean ($76), grain sorghum and wheat-soybean doublecrop ($64), and monocrop grain sorghum ($60) systems were significantly higher than from the monocrop soybean ($25), monocrop corn ($-9), and corn and wheat-soybean doublecrop ($16) systems. Average net returns per acre from the wheat-soybean doublecrop ($48) and the corn-soybean ($42) systems were similar and in the intermediate range. Data indicate that monocrop corn and soybean systems and the corn-wheat-soybean system are not profitable when grown in nonirrigated environments on clay soils in the lower Mississippi River alluvial plain.

Intercropping corn and soybean for silage in a cool-temperature region: Yield, protein and economic effects

Corn (Zea mays L.) and soybean (Glycine max[L.] Merr.) were intercropped for silage in 1985 and 1986 at the Central Experimental Farm, Ottawa, Canada to evaluate silage yield, protein and economic effects. In both years, a complete 2 × 2 ×3 factorial was analysed for two corn hybrids (dwarf and tall), two corn cropping systems (monocropped and intercropped), and three N fertilizer levels (0, 60 and 120 kg N ha−1). In addition to the complete factorial treatments, monocropped soybeans with 0 kg N ha−1 and an intercrop treatment of dwarf and tall corn at 120 kg N ha−1 were grown. In 1986, four population-density levels of the intercropped tall corn and soybean, at 60 kg N ha−1, were also compared.Total yields averaged over corn hybrids and cropping systems had a quadratic response, increasing from 0 to 60 kg N ha−1 and then decreasing slightly between 60 and 120 kg N ha−1, in both years. Monocrops of corn yielded significantly more in both years than intercrops, except tall-corn intercrops in 1986 grown at monocropped-corn population densities. Both corn and soybean of the dwarf-corn intercrops in the dry year of 1985 had a consistent trend of lower dry-matter and protein yields than in tall-corn intercrops at the same levels of N. These differences did not consistently favour either corn hybrid in 1986.The concentration of crude protein was significantly higher in intercropped than monocropped silage in both years. In 1986, this was also true for the protein yield ha−1. Increasing N application resulted in higher total silage protein concentrations in both years. The total silage protein concentration was, on average, 1.53 and 2.15 percentage points higher in intercrops than in the corresponding monocropped corn hybrid at the same level of N in 1985 and 1986, respectively. The total silage protein concentrations in both years and the protein yield in 1986 were greater for tall corn than for dwarf corn.All treatments at 0 kg N ha−1, the dwarf-corn intercrops in 1985 and monocropped dwarf corn at 120 kg N ha−1 in both years, were less cost-effective than the standard, monocropped tall corn at 120 kg N ha−1. In 1985, the tall corn intercrop at 60 kg N ha−1 had a $135 ha−1 cost-effective advantage over the standard treatment. In 1986, this intercrop had a $132 ha−1 advantage, which was improved to $261 ha−1 when the corn population was maintained at monocrop levels and the population of soybeans was reduced by 50%. Land equivalent ratios (lers) based on dry-matter weights ranged from 0.97 to 1.11 in dwarf-corn intercrops and from 1.16 to 1.23 in tall-corn intercrops in 1985. The ler range in 1986 was from 1.11 to 1.12 in dwarf-corn intercrops, and from 1.04 to 1.23 in tall-corn intercrops.

Evaluating Ten Cropping Alternatives for the Midsouth1

AbstractMany crop production systems and cropping sequences are available in the Midsouth and each differs in its management and potential contribution to net farm income. This paper considers several of these variables using yields and costs of production data from a 3‐yr crop production study in Mississippi. A nonirrigated experiment was conducted on Leeper silty clay (fine montmorillonitic, nonacid, thermic Vertic Haplaquepts) from 1976 through 1980. The experiment contained 10 treatments of five monocrop and five doublecrop enterprises in randomized block design. Monocrops were commercial hybrid corn (Zea mays L.), soybean [Glycine max (L.) Merr.], grain sorghum [Sorghum bicolor (L.) Moench], sunflower (Helianthus annuus L.), and wheat (Triticum aestivum L.). Doublecrops were wheat followed by the first four monocrops plus an experimental, insect and disease resistant corn hybrid. Yield and production records were maintained and used to calculate net returns for the cropping alternatives. The five enterprises with highest net returns per hectare (in descending order) were monocrop corn ($495), doublecropped wheat‐soybean ($407), monocrop soybean ($326), doublecropped wheat‐resistant corn ($306), and doublecropped wheat‐sunflower ($285). The farming system that most fully utilized a complement of sixrow equipment and associated power units, and maximized net farm income above variable costs, machinery ownership costs, and land costs was calculated to be 279 ha of cropland as determined by linear programming techniques. This 279 ha would be partitioned as follows: monocrop corn (120 ha), monocrop wheat (13 ha), doublecropped wheat‐resistant corn (62 ha), and doublecropped wheat‐soybean (84 ha). Net return above specified expenses was computed to be $45 897 annually.

Agronomic Cropping for Maximum Biomass Production1

AbstractWith recent widespread awareness of dwindling petroleum supplies, considerable attention has been directed towards plants as photosynthetic energy converters. The purpose of this 3‐year study was to investigate the bioproductivity of agronomic crops as a potential energy source in Minnesota. Experiments were conducted in the field at St. Paul on a Waukegan silt loam (Typic Hapludoll) and at Waseca on a Webster clay loam (Typic Haplaquoll). Both double‐cropping and monocropping systems were evaluated. The double‐cropping system consisted of growing fall‐planted winter rye (Secale cereale L.) at recommended seeding rates and harvesting it on 15 June, near the peak of its vegetative production and before the formation of acceptable grain. After the rye was harvested, the plots were fertilized, disked, and planted to corn (Zea mays L.). Three corn hybrids: ‘Pioneer 3780’ (full season), ‘NKPX74’ (14% more than full season), and ‘Pioneer 3030’ (28% more than full‐season) were grown at each of two populations that exceeded normal production populations by approximately 25% and 100% (75,000 plants/ha and 125,000 plants/ha). Corn was chosen to follow the rye for double‐cropping since, in a preliminary study, we determined that it produced more biomass than sorghum (Sorghum bicolor [L.] Moench) or sudangrass (Sorghum blcolor [L.] Moench) when grown on rye plots following the rye harvest. A corn‐only or monocropping system was established adjacent to the double‐cropping plots. The same three corn hybrids were grown at the same two populations, but they were planted as early in the season as possible and grew uninterrupted. Rye produced an average biomass yield (dry weight of aboveground portion) of 9.6 metric tons/ha (MT/ha) by 15 June. The largest average biomass yield from corn planted after the rye harvest (double cropped) was 16.3 MT/ha, produced by NXPX74 at 125,000 plants/ha. The rye plus corn double‐cropping yields thus averaged 25.9 MT/ha. The largest average monocropped corn yield of 18.8 MT/ha (produced by NKPX74 at 125,000 plants/ha) was 7.1 MT/ha below the double‐cropped yields. Due to interactions and yield fluctuations across environments, however, the two systems were not determined significantly different. Since costs and risks of successfully producing two crops per season would be an important consideration, we suggest that monocropped corn would be preferred over rye‐corn double cropping as a biomass production system in Minnesota.