Bulletin No Corn Silage - Population & Nitrogen

Transcription

1 University of Wyoming Wyoming Scholars Repository Wyoming Agricultural Experiment Station Bulletins Agricultural Experiment Station Bulletin No Corn Silage - Population & Nitrogen University of Wyoming Agricultural Experiment Station Follow this and additional works at: Part of the Agriculture Commons Publication Information University of Wyoming Agricultural Experiment Station (1964). "Bulletin No Corn Silage - Population & Nitrogen." University of Wyoming Agricultural Experiment Station Bulletin 412, This Full Issue is brought to you for free and open access by the Agricultural Experiment Station at Wyoming Scholars Repository. It has been accepted for inclusion in Wyoming Agricultural Experiment Station Bulletins by an authorized administrator of Wyoming Scholars Repository. For more information, please contact scholcom@uwyo.edu.

2 >/*,.,/ du? l " - >, CORN SILAGE POPULATION & NITROGEN BY H. W. HOUGH / L. I. PAINTER "SRICULTURAL EXPERIMENT STATION / UNIVERSITY OF WYOMING -BRUARY 1964 BULLETIN 412

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4 Effects of Corn Population and Nitrogen Fertilization on Economical Production of Corn Silage in Wyoming By H. W. Hough and L. /. Painter 2 gean AND SUGAR BEET GROWERS have encountered plant disease and soil problems that often seriously curtail their production. Cattle and sheep producers have shown interest in enlargement of local feedlot activities. Vt here adapted, corn excels all other forage crops in average yield of dry matter and of digestible nutrients per acre when the entire corn plant is used for silage. Thus a well-managed corn silage program should occupy an increasingly competitive position in irrigated rotations with alfalfa, beans, and sugar beets. The common practice has been to raise dual purpose corn (silage and/or grain) in rotations with beans, alfalfa, small grain, and sugar beets. Attempts by various growers to select varieties, plant populations, and fertilizer practices have not been consistently successful in quantity and quality of silage produced. Hence Wyoming growers have been reluctant to change from their present cultural system. Suitable corn varieties and considerable knowledge of fertilizer requirements are now available for specialized corn silage production on irrigated lands. However, the effects of plant populations and of nitrogen-fertilization rates on yields of irrigated corn silage and associated net returns have not been sufficiently defined. DESCRIPTION OF STUDIES The primary objectives were to determine the effects of plant populations and of nitrogen-fertilization rates on corn-silage production in three irrigated regions of Wyoming. An appraisal is also made of the costs and returns expected with different combinations of nitrogen fertilization and plant population in each of the areas. Corn varieties were chosen that would produce dented kernels by the normal harvest time for silage. Plant populations of 15,000, 25,000, and 35,000 plants per acre were used in combina ' This study was financed in part by monetary and materials grants from Phillips Petroleum Co. - Assistant Professor and Professor of Soils, Plant Science Division, University of Wyoming, respectively. Acknowledgment is made to Wayne Anderson, Ned Case, Marvin Fischer, and Jay Partridge, Univ. of Wyo. soil technicians, for valuable assistance in the field. 3

5 tion with nitrogen-application rates of 0, 40, SO, and 200 lbs. of N per acre. Replicated field plots of four 36-in. rows 50 ft. long were established for each treatment, the nitrogen being side-dressed when the corn was 5 to 6 in. tall on the sandy clay loams at Powell and Riverton. Side-dressing the nitrogen on corn was done at 12 to 18- inch plant height to minimize nitrogen losses on the loamy sand at Torrington. All plots were surface irrigated approximately 8 times per season at Powell, 7 at Riverton, and 5 at Torrington. The two center rows of each plot were harvested for yield and quality determinations. The silage yields presented in this publication are the means of four years at Powell, three years at Riverton, and one year at Torrington. Weight of the snapped ears for two seasons at Powell and crude-protein percentages of silage for two seasons at Powell and for one season at Riverton were taken to indicate quality responses to nitrogen-application and plant-population variables. The plot areas were generally chosen to follow small grain in the rotation on the principal irrigated soil for the respective project areas Garland sandy clay loam for Powell, Lost Wells' sandy clay loam for Riverton and Dwyer, and Valentine or Lihen loamy sand for Torrington. Differences in soil, management, operation costs, and crop values occur from farm to farm and from area to area. It is hoped that these differences were held to a minimum for these trials by using the principal irrigated soil in each of these areas as well as a definite cropping system. YIELD I Silage Yield The corn-silage-yield responses to various plant populations and nitrogen application rates are shown in Figure 1 for Powell, Figure 2 for Riverton, and Figure 3 for Torrington. The increase in yield (Table 1) due to added nitrogen at all locations was less for the smaller plant populations than for the denser populations at the lower nitrogen rates. Forty pounds of nitrogen at Riverton and 80 lbs. at Torrington were required to obtain silage yields comparable to unfertilized plots at Powell. Maximum yields for the two higher populations at all locations were comparable. At Powell, the yield difference between 15,000 and 25,000 plants per acre and between 25,000 and 35,000 plants per acre were approximately equal at all nitrogen rates. At Riverton and Torrington the yield differences between 15,000 and 25,000 plants per acre were four to five times as great as the differences between 25,000 and 35,000 plants per acre. The 35,000- plant population at all locations required only 80 lbs. of applied nitrogen per acre to produce the same tonnage of silage as 15,000 plants per acre did with 160 lbs. of nitrogen. '/Not a correlated series. 4-

6 Silage Quality Wyoming growers prefer a corn silage with a relatively high ear content at shown in Figure 4. The higher populaearly-dent stage. The weight of ears in silage determined for the Powell test is tions required 80 to 120 lbs. of N ap- 35,000 PLANTS/A. Y= N O N 2 5,000 PLANTS/A. Y = N N 2 1 5,000 PLANTS/A N N 2 3 5,000 >5, , POUNDS NITROGEN APPLIED PER ACRE 200 FIGURE 1 CORN SILAGE YIELD RESPONSE TO INCREASED STAND COUNTS AND NITROGEN- FERTILIZER APPLICATIONS AT POWELL, WYOMING 5

7 TABLE 1 FIELD-RUN CORN-SILAGE YIELDS FOR THREE PLANT POPULATIONS AND SEVERAL NITROGEN-FERTILIZER RATES AT POWELL. RIVERTON, AND TORRINGTON SILAGE YIELDS (TONS AT 70% MO ISTURE / ACRE )' LBS. A 1 5,000 PLANTS /ACRE 25,000 PLANTS/ACRE 35,000 PLANTS / ACRE POWELL RIVERTON TOR RING TON / EACH INCREASE OF PLANTS PER ACRE REQUIRES 7 1/2 MORE LBS SEED WHEN MEDIUM FLATS ARE USED. plied per acre to produce a significantly greater weight of ears than the plant populations. This population essentially reached its maximum weight of ears per acre at 120 lbs. of applied nitrogen per acre, while the ear weight of the other two populations increased with higher nitrogen rates. Figure 5 shows the percentage of silage weight due to ears. The 25,000- plant population required 90 lbs. of N per acre and the 35,000-plant population required 115 lbs. N per acre to produce an ear weight proportionally equal to that produced by the 15,000- plant population. The two higher plant populations produced equal ear proportions at 160 lbs. N per acre. Another quality feature in corn silage is its crude-protein content. Additional protein is usually fed when feeding corn silage. However, well-fertilized corn

8 may produce silage containing twice the crude-protein content of corn receiving no nitrogen applications. The effects of increasing amounts of applied nitrogen on crude-protein characteristics of corn silage during two growing seasons are shown in Figure 6 for crude-protein percentage and in Figure 7 for pounds 3 5,000 PLANTS/A. Y = N N 2 25,000 PLANTS/A.?= N N 2 1 5,000 PLANTS/A. Y= N N 2 35,000 - *25,000 " i5.o -y 1 20 POUNDS NITROGEN APPLIED PER ACRE FIGURE 2 CORN SILAGE YIELD RESPONSE TO INCREASED STAND COUNTS AND NITROGEN- FERTILIZER APPLICATIONS AT RIVERTON, WYOMING

9 o POUNDS NITROGEN APPLIED PER ACRE FIGURE 3 CORN SILAGE YIELD RESPONSE TO INCREASED STAND COUNTS AND NITROGEN- FERTILIZER APPLICATIONS AT TORRINGTON, WYOMING

10 TABLE 2 INFLUENCE OF PLANT POPULATION ON CRUDE-PROTEIN PERCENTAGE AND CRUDE- N POWELL 1961 POWELL 1962 RIVERTON 1961 PLANTS CRUDE PROTEIN % CRUDE PROTEIN LBS / A CRUDE PROTEIN % CRUDE PROTEIN LBS / A CRUDE PROTEIN % CRUDE PROTEIN LBS / A 1 5, * 3.11 * ' 899* 25, ' 2.83* 1374* 2.13* 999'* 35, * 1231 * 2.79* * 2.16* # t / MEANS OF FOUR REPLICATIONS. MEANS WITH THE SAME LETTER SUPERSCRIPT WITH IN ANY ONE COLUMN ARE NOT STATISTICALLY DIFFERENT FROM EACH OTHER AT THE.05 LEVEL OF SIGNIFICANCE. of crude protein produced per acre. The added nitrogen increased both the percentage and the production of crude protein. The annual differences in crude-protein production at Powell were considerably smaller above the 120 lbs. N/A application rate than they were below. Locational differences in crude-protein yield persisted throughout the range of nitrogen applications used. Plant-population influences (Table 2) were very slight for either percentage or production of crude protein. ECONOMIC CONSIDERATIONS The yield responses to plant populations and to fertilizer rates are shown in the preceding section. The selection of proper rates of each for maximum net returns from seed and fertilizer investment involves comparisons of expected added costs to expected added returns. The following costs were used in analysis of this study: $12.00/bu. for hybrid seed (medium flats), Sl.OO/acre fertilizer-application cost, S1.25/ton silage-harvest cost, 13c/lb. for nitrogen at the field, and credit charges of 7 percent interest for 6 months on seed and fertilizer. Yields, probable costs, and three sales prices are compared in Tables 3, 4, and 5 to show the rates of application which usually would return the highest profit for the seed and fertilizer investment. For the costs, prices, and rates used, the highest returns per acre for each plant population are underlined in Tables 3, 4, and 5. The tests at Powell with field-run silage valued at $4.00 per ton indicated the highest returns would be at 35,000 plants per acre with 120 lbs. N/A. At 25,000 and 15,000 plants per acre, fertilization with 80 lbs. N/A gave the highest returns. For field-run silage valued at $6.00 per ton, the highest returns would be obtained at 35,000 plants per acre with 160 lbs. N/A. At 9

11 25,000 plants per acre, fertilization with 160 lbs. N/A would be preferable, but at 15,000 plants per acre the best fertilization rate would be 120 lbs. N/A. In assuming silage worth $8.00 per ton, the highest returns within each of the three populations would be obtained by using 160 lbs. N/A. However, the returns from the 35,000 plants per acre would be higher than those from the 25,000-plant population, which in turn are higher than those from the 15,000- plant population. At Riverton, with field-run silage 35,000 - u 5 Z 111 o Y = tN N I4376P P NP _1 L NITROGEN APPLIED (LBS/A.) FIGURE 4 REGRESSION OF EAR WEIGHT IN SILAGE PRODUCED ON NITROGEN APPLIED TO POPULATIONS OF 15,000; 25,000; AND 35,000 PLANTS PER ACRE (POWELL, WYOMING,1959 AND 1961) 10

12 NITROGEN APPLIED (LBS/A.) FIGURE 5 INFLUENCE OF PLANT POPULATION AND NITROGEN APPLICATIONS ON PERCENTAGE OF CORN-SILAGE WEIGHT DUE TO EARS (POWELL, WYOMING,1959 AND 1961) 11

13 TABLE 3 TOTAL ADDED RETURNS MINUS ADDED COST FOR FIELD-RUN SILAGE AT THREE DIFFERENT PRICES AS INFLUENCED BY NITROGEN-FERTILIZER RATES AND THREE PLANT POPULATIONS (GARLAND CLAY LOAM NEAR POWELL, WYOMING) NITROGEN APPLIED TOTAL ADDED RETURNS MINUS ADDED COSTS 1 ( $) / ACRE LBS./A PLANTS /ACRE PLANTS / ACRE PLANTS / ACRE $ 4.00 PER TON OF FIELD-RUN SILAGE $ 6.00 PER TON OF FIELD-RUN SILAGE $ 8.00 PER TON OF FIELD-RUN SILAGE J / BASED ON 13ff / LB. OF NITROGEN AT THE FIELD. $ 1.00/ ACRE SPREADING COST. S BU. FOR SEED CORN. AND 7% INTEREST FOR 6 MONTHS (18 9 FOR 40 LBS. N AND 6 9 FOR 7 1 /2 LBS. SEED \ AND $ 1.25 A TON ADDITIONAL COST TO CUT AND PLACE IN THE SILO. 2/ HIGHEST DOLLAR RETURNS PER ACRE FROM NITROGEN APPLICATION FOR EACH SILAGE PRICE AND PLANT POPULATION ARE UNDERLINED IN THIS TABLE. valued at $4.00 per ton the trials indicated the highest returns at 35,000 plants per acre with 120 lbs. N/A. With 25,000 plants per acre, fertilization with 120 lbs. N/A. would be preferable, but at 15,000 plants the best fertilization rate would be 80 lbs. N/A. For the $6.00 and $8.00 values per ton of field-run silage the highest returns would be obtained at 35,000 plants per acre and 160 lbs. N/A. At plants per acre, fertilization with 160 lbs. N/A. would also be preferred, and all the plant population 120 lbs. N/A. would be the best rate. At Torrington for field-run silage valued at $4.00 per ton, the trials indicated highest returns at 35,000 plants per acre with 160 lbs. N/A- At the 25,000-plant population, fertilization with 160 lbs. N/A. would be the best rate while at the 15,000-plant population, fertilization with 120 lbs. N/A. would be preferred. For the $6.00 and $8.00 prices per ton of field-run silage the highest returns would be obtained at 35,000 plants per acre with 160 lbs. N/A. At the 25,000-plant population, fertilization with 200 lbs. N/A. would be the best rate, but for the 15,000- plant population the best fertilization rate would be 160 lbs. N/A. For all silage prices used, the highest returns were indicated for the 35,000- plant population. The amount of fertilizer used to achieve these results varied 12

14 POUNDS NITROGEN APPLIED PER ACRE FIGURE 6, REGRESSION OF CRUDE-PROTEIN PERCENTAGE rn CORN SILAGE ON POUNDS NITROGEN APPLIED PER ACRE 'means of the three populations used TABLE 4 TOTAL ADDED RETURNS MINUS ADDED COST FOR FIELD-RUN SILAGE AT THREE DIFFERENT PRICES AS INFLUENCED BY NITROGEN-FERTILIZER RATES AND THREE PLANT POPULATIONS ( LOST WELLS SANDY CLAY LOAM NEAR RIVERTON, WYOMING) TOTAL ADDED RETURNS MINUS ADDED COSTS ' ($ )/ACRE NITROGEN APPLIED LBS./A PLANTS ' ACRE 25,000 PLANTS /ACRE 35,000 PLANTS 7 ACRE $ 4.00 PER TON OF FIELD-RUN SILAGE $ 6.00 PER TON OF FIELD-RUN SILAGE $ 8.00 PER TON OF FIELD-RUN SILAGE «/ BASED ON 13 */LB. OF NITROGEN AT THE FIELD, S I.00/ACRE SPREADING COST, S I 2.00 / BU FOR SEED CORN. AND 75? INTEREST FOR 6 MONTHS (18 e FOR 40 LBS. N AND 6 «FOR 7 1/2 LBS. SEED ^ AND S 1.25 A TON ADDITIONAL COST TO CUT AND PLACE IN THE SILO. */ HIGHEST DOLLAR RETURNS PER ACRE FROM NITROGEN APPLICATION FOR EACH SILAGE PRICE AND PLANT POPULATION ARE UNDERLINED IN THIS TABLE. 13

15 TABLE 5 TOTAL ADDED RETURNS MINUS ADDED COST FOR FIELD-RUN SILAGE AT THREE DIFFERENT PRICES AS INFLUENCED BY NITROGEN-FERTILIZER RATES AND THREE PLANT POPULATIONS ( DWYER LOAMY SAND NEAR TORRINGTON, WYOMING ) NITROGEN APPLIED TOTAL ADDED RETURNS MINUS ADDED COSTS' ($ )/ACRE LBS./A. I 5,000 PLANTS/ACRE 25,000 PLANTS/ACRE 35,000 PLANTS/ACRE $4.00 PER TON OF FIELD-RUN SILAGE $ 6.00 PER TON OF FIELD-RUN SILAGE $ 8.00 PER TON OF FIELD-RUN SILAGE I / BASED ON 13» / LB. OF NITROGEN AT THE FIELD, $ I.00/ACRE SPREADING COST, $ /BU. FOR SEED CORN, AND T% INTEREST FOR 6 MONTHS (1 8 f FOR 40 LBS. N AND 6 9 FOR 7 I /2 LBS. SEED),AND $ 1.25 A TON ADDITIONAL COST TO CUT AND PLACE IN THE SILO. 2/ HIGHEST DOLLAR RETURNS PER ACRE FROM NITROGEN APPLICATION FOR EACH SILAGE PRICE AND PLANT POPULATION ARE UNDERLINED IN THIS TABLE. from 120 lbs. N/A. to 160 lbs. N/A., depending on the price of silage. The selected prices per ton of silage in Tables 3, 4, and 5 are the same regardless of silage quality. However, as shown in Figure 5, 120 lbs. N/A. produced ear-weight proportions in the silage from the population equal to or better than those produced with the 15,000 population. For equal earweight proportions in the silage from the 25,000 and 35,000 populations, 165 lbs. N/A. was required. While no price adjustment was set for the ear-proportion quality of silage, the fact that it was somewhat deficient in the 80 lbs. N/A. for 25,000 plants per acre at Powell and in the 120 lbs. N/A. for 35,000 plants per acre for Powell and Riverton makes the selection of seeding and fertilization rates important if nutritional quality as well as profit is to be considered. 14

16 I AVAILABLE NITROGEN APPLIED (LBS/A.) FIGURE 7 EFFECT OF NITROGEN-FERTILIZER APPLICATIONS ON SILAGE-CORN CRUDE-PROTEIN PRODUCTION. 1 1 MEANS ON THE THREE POPULATIONS USED. 15

17 CONCLUSIONS 1. Application of nitrogen fertilizer increased both the yield and the crudeprotein percentage of silage harvested from all three populations used, but affected the ear-weight proportions only in the 25,000 and 35,000-plant populations. 2. Plant populations of 15,000, 25,- 000, and 35,000 plants per acre caused significant differences in silage yields per acre and in ear-weight proportions of harvested silage for any given rate of nitrogen application. 3. Comparisons of added returns minus added costs for the three trial areas at three different prices for fieldrun silage indicated the most profitable rates of nitrogen applications used with each of three plant populations were as shown in Table 6. TABLE 6 MOST PROFITABLE NITROGEN-APPLICATION RATE (LBS N/A) PRICE $ /TON OF PLANT POPULATIONS PER ACRE LOCATION FIELD-RUN SILAGE 15,000 25,000 35,000 POWELL RIVERTON I TORR INGTON M-10 University of Wyoming Agricultural Experiment Station N. W. Hilstan, Director Laramie 16