Information from 2000 Missouri Rice Research Update, February 2001.

Corn After Rice: Results of 2000

Michael Aide and Monica Siler, Southeast Missouri State University
David Dunn and Gene Stevens

The purpose of this research project is to determine if the soil fertility and the physical status of the soil are impacted by rice and if these soil changes are detrimental to the growth of corn. As a corollary, this project hopes to provide cost efficient farming operations to improve the growth of corn.

Two experiments were conducted during 2000; (1) a study to determine if soil hipping was a better agronomic tillage option than no-till planting, and (2) a study to assess corn growth on land that had been planted previously in: (i) soybeans, (ii) drill-seeded rice, and (iii) water-seeded rice.

Experiment #1 was conducted at the Missouri Rice Research and Demonstration Farm on a somewhat poorly drained Crowley silt loam with a satisfactory soil fertility level (Table 1).

The experimental design consisted of separate plots for the raised and flat beds. Each plot consisted of nine rows, each having a length of approximately 200 feet. Raised and flat beds had a row spacing of 36 inches. Nitrogen fertilizer (Urea) was applied according to soil test at planting. Irrigation was flood, followed by draining.

After planting, the bulk density and saturated hydraulic conductivity were determined. Measurements were taken in triplicate for the raised bed, the flat bed, and the underlying subsoil. Additionally, the distribution of the soil aggregates was estimated using dry sieving.

Tissue testing was performed five times; 22 May, 6 June, 27 June, and 17 July. These samples were analized for N,S, P, K, Ca, Mg, Na, Al, Fe, B, Mn, Cu and Zn. Roots were similarly collected (6 June and 17 July) and analized for the same 13 elements.

Total plant biomass was assessed twice during the growing season. Four visually representative plants were selected for analysis from each plot.. Roots, stems (culms), leaves, tassels, and ears were separated and dried at 70 C for several days and weighed.

The soil bulk density is low, indicating a pore space of approximately 58% for the hipped and flat surface soil layers (Table 1). The bulk density of the subsoil is appreciably higher, indicating a more compact soil layer and a reduced total pore space. Additionally, the compact subsoil has the likelihood of restricting the developing root system of corn because of reduced soil temperatures, wetness, and physical hindrance of the elongating roots.

Tissue testing demonstrates that the nutrient levels for the corn plant are appropriate, suggesting that the soil fertility has not hindered plant growth (Table 2). Root tissues are generally lower in the macronutrients than the leaf tissues; however, selected micronutrients such as Fe and Mn are appreciably greater in root tissues, indicating root accumulation. Nutrient levels of the hipped and the flat tillage designs are simalar, indicating that any yield differences between these two treatments are not attributable to soil fertility.

The total plant biomass and the distribution of the biomass among the root system, stem, leaf and ear indicate differences because of the tillage treatments (Fig. 1). Total biomass, stem and root growth are appreciably greater in the hipped system. The leaf to root ratio for the hipped system (1.24) was significantly lower than leaf to root ratio for the flat system (2.0 ). Average plant height was significantly greater for the hipped system (67 inches) than the flat system (58 inches). Yield estimates indicate that the hipped system returned 105 bu/a, whereas the flat system returned 84 bu/a.

Experiment two was conducted in a commercial field where corn was planted after a previous crop of (i) soybeans, (ii) drill seeded rice and (iii) water seeded rice. The soil type was a somewhat poorly drained Crowley silt loam with a satisfactory soil fertility level (Table 3). Fertilization consisted of 90 lbs of urea, 90 lbs of a (0-23-30) mixed fertilizer at planting and 200 lbs of liquid N after emergence. Planting dates for corn were 7 April (soybeans and drilled seeded rice plots) on 29 inch rows. Corn was planted on 13 April for the water seeded rice plots on 31 inch rows. Irrigation was furrow irrigation. All methods of data collection are similar to those described for Experiment #1.

Tissue testing demonstrates that the nutrient levels for the corn plant are appropriate, suggesting that the soil fertility has not hindered plant growth (Table 2). Root tissues are generally lower in the macronutrients than the leaf tissues; however, selected micronutrients such as Fe and Mn are appreciably greater in root tissues, indicating root accumulation. Nutrient levels of the soybean, drill seed and water seeded designs are largely simalar, indicating that any yield differences between these three treatments are not attributable to soil fertility.

The total plant biomass and the distribution of the biomass among the root system, stem, leaves and ears indicate differences because of the previous crop (Fig. 2). Total biomass, ear, stem leaves and root growth are appreciably greater in corn-after-soybean systems than either of the corn-after-rice systems. The corn after drill-seeded rice produced a greater total biomass and greater biomass among the root system, stem, leaves and ear than the corn after water-seeded rice (Fig. 2). The leaf to root ratio for the corn after soybean system (1.76) was similar to the leaf to root ratio for the corn after rice systems (1.8). Average plant height for the corn after soybean system (68.5 inches ) was roughly equivalent to the corn-after-drill-seeded rice (71.3 inches) and significantly greater than the corn-after-water seeded-rice (52.5 inches).

Yield estimates indicate that the corn after soybean system returned 153 bu/a and the corn-after-drill-seeded rice system returned 155 bu/a. The corn-after-water-seeded rice system returned 104 bu/a.

1. Soil fertility did not appear to be a deciding factor in the development of corn between rotations involving corn-soybeans and corn-rice.

2. Physical properties of the soil suggest that the total pore space is normal for a silt loam soil; however, the distribution of the pores is such that the majority of pores are small. The lack of significant soil structure and the large percentage of small pores likely resulted from the slaking of the soil structure during flooding of the previous rice crop.

3. Hipping promoted corn growth and yield, suggesting that the tillage system provided a more suitable rooting environment.

Table 1a. Soil test and physical property characterization of hipped and flat planted corn.

Table 1b.

Table 2. Nutrient concentrations in the developing corn crop.

Table 3. Soil test and physical property characterization of corn ground following soybeans, drill seeded rice and water seeded rice.

Table 4. Tissue test results for corn following soybeans, drill seeded rice and water seeded rice.

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