irlfvTexas .A&M University gricultural Experiment Station son, Director, College Sfclfion, Texas Response of Irrigated Crops To Micronutrients In t/m flan/er Kin firande Vallqz/ B-l004 January, I964 éontmts %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% INTRODUCTION ...................................................... SOME FACTQRS INFLUENCINQ MICRONUTRIENT AVAILABILITY a ' ‘.5 CAUSING MICRONUTRIENT DEFICIENCIES Previous Land Use ............................................. Soil and Climatic Conditions ............................... Land Leveling ........................................................ -. Excessive Alkalinity and Salinity ....................... Nutrient Imbalance ............................................... Fertilizer Practices and Technology ................... .. RESEARCH RESULTS ........................................... Field-screening Trials .............................................. -- Experimental Procedures .................................... Results and Discussion ....................................... Beans .................................................................. .. Beets .................................................................... Broccoli ............................................................... Cabbage ------------------------------------------------------------- Carrots ............................................... --; ............ Field Corn .......................................................... e Sweet Corn ......................... ............................. CQttQn _________________________________________________________________ Grain Sorghum ................................................ -.* Onions ................................................................. Peas -------------------------------------------------------------------- Potatoes ............................................................. Spinach -------------------------------------------------------------- Sudan ................................................................ Hi Squash ............................................................... Tomatoes .......................................................... .. Phosphorus-Zinc Interaction Research ................. Experimental Procedure .................................... Field Experiments .......................................... up» Greenhouse Experiments ............................. .- Analytical Procedures .................................... -.yf Results and Discussion ................................. 1958 Field Experiment ................................. 1959 Field Experiment .................................. Greenhouse Experiment ....... -- Conclusions .......................................................... GENERAL CONCLUSIONS AND COMMENTS ROLE of the micronutrients zinc, iron, ise, boron, copper and molybdenum in ~ ritio-n has been reviewed in recent years -: researchers (1, 6, 9, 11, 16, 20). These l? elements, often referred to as “minor” _” elements, are no less important than i plant nutrients but are required only amounts. However, a deficiency of any micronutrients will limit plant growth {drastically as a deficiency of any of the .1 (N, P and K) or secondary (Ca, Mg and l'ents. ronutrient deficiencies have been ob- n a number of Valley crops and over a _, ge of soil and climatic conditions. Al- ‘such deficiencies have occurred with in- f frequency in recent years, there is no I believe that micronutrient deficiencies soils are widespread. However, under i=soil and climatic conditions, deficiencies , and crops will respond to applications in micronutrients. ‘Factors Influencing Micronutrient ifrilability Causing Micronutrient Deficiencies umber of factors may influence micro- , availability and may cause micronutrient "ies in plants. Some of these factors are _-: land use, soil and climatic conditions, eling, excessive alkalinity and salinity, imbalance and fertilizer practices and l s Land Use ,, sive cropping of land, soil erosion and iequent depletio-n of organic matter re- j a rapid depletion of available mi- ents. Decomposing organic matter is an “t source of available micronutrients, soils excessively cropped and depleted ic matter may not be able to supply f amounts of micronutrients to meet crop ents. lid Climatic Conditions fer abnormal soil and climatic conditions, trient deficiencies frequently may occur plly would not develop under more favor- ely, associate agronomist, associate soil physi- j superintendent, Lower Rio Grande Valley Ex- : Station, Weslaco, Texas. Response of Irrigated Crops to Mieronutrients In the flan/er Kia flandc Valley C. A. Burleson, C. l. Gerard and W. R. Cowley* able growing conditions. Crops growing in cold, wet soils may be unable to obtain sufficient mi- cronutrients for normal growth because of limit- ed root extension under such conditions. Exces- sive rainfall or irrigation may possibly reduce the uptake of available micronutrients by crea- ting an unfavorable root environment. On the other hand, excessively dry soil conditions during the period of heavy demand for nutrients may restrict the movement of micronutrients into plants, thus causing temporary deficiencies. Many of the micronutrient deficiencies in Rio Grande Valley crops are often related to unfavorable climatic conditions during the early stages of growth and to unfavorable root environment as a result of poor soil and Water management prac- tices. Land Leveling Micronutrient deficiencies occur frequently Where deep cuts are made during land-forming operations, leaving exposed subsoils. Such ex- posed areas usually are low in organic matter and are in poor physical condition, resulting in poor root development. As a result, plants fre- quently are unable to obtain adequate amounts of micronutrients from the exposed subsoils. Under such conditions, crops in these areas frequently exhibit symptoms of micronutrient deficiencies which result in decreased yields. Excessive Alkalinity and Salinity The solubility of the micronutrients and their subsequent uptake and utilization by plants may be significantly reduced under conditions of high alkalinity. Generally the solubility of the micronutrients and their availability to plants progressively decreases as the pH of the soil increases from 6.5 to 8.5. In addition to the effect of pH on micronu- trient availability, saline and alkaline conditions also may provoke micronutrient deficiencies by affecting their uptake as a result of abnormal plant growth and soil environment. Under saline and alkaline conditions, water movement into plants is restricted. Under these conditions plants are often stunted and an imbalance of ions as a result of saline conditions usually exists. All of these conditions interfere- with the normal nutrition of plants. In general, micronutrient deficiencies caused by such conditions are best corrected by first altering the conditions re- sponsible for their occurrence. Nutrient Imbalance When one plant nutrient or mineral element is out of balance with other elements, certain micronutrient deficiencies may also be induced. For example, high concentrations of soluble phos- phorus from applied phosphorus have induced zinc deficiencies in certain crops in some Valley soils. Researchers in California have reported that accumulations of soluble phosphorus in the soil will cause deficiencies of boron and copper (7) in citrus. Although the mechanism involved in the induction of zinc and other micronutrient deficiencies by phosphorus is not fully under- stood, research information available to date sug- gests that an antagonism occurs between phos- phorus and certain micronutrients within the root or at root surfaces. Another example of the importance of nutrient balance is the relationship between calcium and boron. The uptake of boron in soils is affected by the level of soluble calcium. A certain balance between these two nutrients is necessary for normal plant growth. This balance may vary with different crops. The occurrence of iron chlorosis in crops, caused by the inactiva- tion of iron within plants, is often found in soils high in calcium carbonate content. This is gen- erally referred to as lime-induced iron chlorosis. Other examples could be cited to show how an excess or deficiency of one element may affect the availability of others. Fertilizer Practices and Technology The change from the use of low analysis fertilizers, containing micronutrients as impuri- ties, to the use of large amounts of high analysis fertilizers, containing few micronutrients as im- purities, has contributed to the occurrence of micronutrient deficiencies and possibly acceler- ated the need for additions of micronutrients to crops and soils sooner than if low analysis ferti- lizers were still used. However, the economic advantage gained from the use of high analysis fertilizers more than offsets any disadvantages. TABLE 1. THE EFFECTS OF SEVERAL CHELATED TRACE-MINERALS ON THE YIELD OF SEVERAL CROPS IN THE LOWER RIO GRAN OF TEXAS IN 1963 I Research Results Field-screening Trials EXPERIMENTAL PROCED URES Research was initiated in 1958 to certain horticultural and agronomic crops under irrigation for response to micronut‘ Field trials were conducted on Harling and on Willacy and Hidalgo sandy loam so, In all field trials, a randomized bl perimental design was used. Treatmen =; replicated from four to seven times in the ~- tests. Four-row plots, 40 to 50 feet Ion»; used. . In all field screening trials, the sou _ micronutrients were mixed with 60 po if nitrogen from ammonium sulfate and =2‘ just before planting in a band 2 to 3 inc, the side and below the seed zone. With; planted on single 40-inch rows, only one b fertilizer was used. With crops planted two to the bed, such as with some vegetablj fertilizer materials were banded below and. side of each of the two rows of vegetablr crops except green beans were sidedress an additional 40 pounds of nitrogen fro monium sulfate. Other cultural practic? carried out in accordance with general pr t l practices of the area. ' RESULTS AND DISCUSSION Results from field tests with micronu on 16 different crops and on one or mo types have- been obtained over a 5-year g Results have often varied from year to} with the same crop often responding diff a A response one year and the lack of respo" the same crop another year would indica climatic or other environmental factors W fecting micronutrient supply and/or avail, Although the data obtained thus far? inconsistent to make general recommen Lint‘ Sweet Chico Field Squash, cotton, Beans, Squash,‘ corn, tomatoes, corn, Pounds pounds bales pounds pounds dozen tons bushels Material per acre per acre per acre per acre per acre per acre per acre per acre ' I Check 15,714 1.00 7,105 5,182 671 23.3 73.5 Fe 138 Sequestrene 1.0 15,026 .96 7,584 5,053 565 23.5 90.3 Fe 138 Sequestrene 4.0 14,520 1.03 7,503 5,010 645 21.7 88.1 NaaZn Sequestrene 1.0 14,737 .94 8,150 5,515 659 21.2 86.0 NaaZn Sequestrene 4.0 14,577 .98 7,219 5,106 682 21.5 94.2 Fe 330 Sequestrene 1.0 15,833 .98 7,714 5,719 608 21.8 101.8 Zn 138 Sequestrene 1.0 16,318 .93 7,862 5,289 642 23.4 92.7 NaaMn Sequestrene 4.0 16,928 .97 7,245 5,364 645 22.4 95.1 N.S. N.S. N.S. N.S. N.S. N.S. N.S. lGrown on Harlingen clay, all others on Hidalgo sandy loam soil. A bale of cotton is considered 500 pounds of lint. Varieties Squash—Yellow Crookneck Beans—-Pearlgreen Cotton—Deltapine TPSA Sweet Corn—-Golden Ban -_ Tomatoes—Chico Field Corn—Texas 30 ‘pistons: o|= GREEN BEANS (PEARLGREEN VARIETY) ,4 IIIDALGO LOAM sou ro FOLIAR APPLICATIONS 1 or mow AND zmc m 196a Greenbeans, Pounds Time of pounds per acre application per acre 7,361 2.0 FB 6,876 4.0 FB 6,518 1.0 FB and WL 8,034 2.0 FB and WL 7,157 2.0 FB 8,282 4.0 FB 7,725 2.0 FB and WL 7,085 1.0 FB and WL 7,350 1.0 FB 7,841 1.0 FB 2.0 FB 7,152 2.0 FB 1.0 FB and WL 7,405 1.0 I applied at rate of 100 gallons of spray per acre. and WL means week later. s “ion a Hidalgo loam soil. iigfimicronutrients on all crops and ficient to- indicate that the use of may be profitable in some years rrops. ~ssion of crop response to the var- _trients is presented by individual a ns for canning purposes are grown lighter textured or sandy loam ghave been screened for response to nganese and copper (Tables 1, 2 é» data presented in Tables 1 and 2 legreen beans will generally respond f of iron and zinc. Burleson, et al. ' that the addition of 10 pounds of 0 iron chelate with 30 pounds of g sed the yield of bean pods by h acre. Data in Tables 1 and 2 igreen beans will respo-nd to both applications of zinc and iron. The .2 would also seem to indicate that , foliar sprays may be important. fn of iron spray applied at the first fa blooms was more effective than when applied at first bloom and a Week later. On the other hand, zinc sprays appeared to be more effective when applied, at first bloom and a week later. Further testing is needed to confirm these indications. Beets Canning beets are grown on both heavy- and light-textured soils. Beets grown in clay soils were screened for response to soil applications of copper, iron and zinc (Tables 4 and 5) . Data from these trials give no indication of a yield response to the micro-nutrients used. Longbrake and Sleeth (15) have previously reported that black spot of beets, caused by a deficiency of boron, can be controlled by foliar applications of Solubor, a readily soluble source of boron. Black spot frequently occurs in Valley beet fields, and its occurrence is encouraged by poor production practices such as inadequate fertilization and moisture stress. It is generally more prevalent in older and mature beets. Broccoli Broccoli grown on Harlingen Clay was screened for response to copper, iron and zinc (Tables 4 and 5). These data do not indicate a response to these micronutrients. Cabbage Results of screening trials with cabbage grown on Harlingen clay to determine response to- soil applications of copper, zinc and iron are shown in Tables 4 and 5. Cabbage did not re- spond to copper (Table 4). Although not sta- tistically significant at the 0.05 level, the data in Table 5 indicate a possible yield response to iron since the three iron treatments gave a yield increase of,a ton or more of marketable cabbage per acre than did the non-treated plots. Further tests are planned to confirm this in- dication of response to iron. Carrots Carrots grown on a Harlingen clay soil in 1962-63 responded significantly to soil applica- tions of both iron and zinc. Both micronutrients resulted in a significant increase in the yield of U. S. No. 1 carrots (Table 6) and a significant decrease in the production of culls. Further NSE OF SEVERAL IRRIGATED CROPS GROWN ON A WILLACY SANDY LOAM SOIL TO VARIOUS MICRONUTRlENTS—1959 Average yield of crops in pounds per plotl Pounds Green Irish Sweet Purplehull Grain Shelled l1 per acre Squash beans potatoes corn Sudan peas sorghum corn a‘ 6.8 12.8 45.9 31.8 7.1 17.7 18.0 13.2 20.0 13.3 12.9 49.9 34.9 7.5 19.8 16.7 21.6 20.0 10.4 13.5 46.4 28.1 7.3 17.2 16.7 27.9 20.0 8.2 11.9 44.1 22.5 7.5 18.7 17.9 19.5 In yield is equivalent to 276 pounds per acre. - neck A run Irish potatoes-—Red I.a Soda Sweet Corn—Golden Bantam Sudan—Sweet Sudan Peas—-Purplehull Groin sorghum—Redbine 66 Field Corn—Texas 3O TABLE 4. THE RESPONSE OF SEVERAL VEGETABLE CROPS TO DIFFERENT RATES AND SOURCES OF COPPER APPLIED TO HARLIN » SOIL 1960-61 ~ gm pounds Yields of vegetables in tons per acre Material per acre Cabbage Spinach Beets Broccoli Squash Sweet corn Check 22.8 11.9 25.5 2.1 1.8 3.8 Copper 5.0 21.1 12.4 24.1 2.6 1.81, 3.7 Copper 10.0 ’ 20.8 11.6 24.8 2.1 1'.~8 3.8 Copper 20.0 20.9 12.8 25.0 2.3 1.7 3.8 Copper 40.0 22.2 11.6 24.4 2.1 1.6 3.6 Copper 5.0 20.4 12.3 25.0 2.5 1.9 3.6 Copper 10.0 19.4 12.7 24.3 2.3 1.8 3.7 Copper 20.0 18.2 10.4 25.7 2.6 1.8 3.7 Copper 40.0 22.1 12.5 24.1 2.1 1.9 2.9 Es-Min-El (100 pounds 3.8 20.7 12.5 25.9 2.3 1.6 3.3 per acre) indicates source of copper was brown copper oxide, 50% Cu; CuSO 39.8% Cu. was used for all other copper sou Spinach—Hybrid 7 Beets—Detroit Dark Red Varieties used Cabbage—GIobe YR trials are planned with vario-us combinations of these two micronutrlents. Field Com Field corn grown on Hidalgo sandy 10am was screened for response to soil applications of zinc, iron, copper and manganese (Tables 1 and 3). Corn responded to all treatments both in 1959 and in 1963. Further tests are needed to deter- mine the best micronutrient combinations, source of materials, rates and frequency of application. Generally corn has been more consistent in its response to zinc. Sweet Corn Sweet corn grown on Harlingen clay soils did not respond to soil applications of copper (Table 4). Sweet corn grown on Willacy fine sandy loam soil in 1959 (Table 3) responded to soil applications o-f zinc sulfate. In 1962 sweet corn did not respond significantly to soil applica- tions of copper, molybdenum, zinc, iron, boron, manganese and Es-Min-El (Table 7). The author, however, has on numerous occasions observed zinc deficiency symptoms in sweet corn. These symptoms were easily corrected when foliar sprays of zinc sulfate were applied when the de- ficiency symptoms first appeared. TABLE 5. THE, RESPONSE OF SEVERAL CROPS TO APPLICATIONS OF IRON AND ZINC CHELATES APPLIED TO A HARLINGEN C Broccoli—Waltham 29 Squash—Ye|Iow Crookneck Sweet Corn-—Golden Ban Onions—L36 Yellow I Cotton Cotton grown on Harlingen clay i did not respond significantly to- periodic?’ applications of boron, iron or zinc (Ta In 1963 cotton grown on Hidalgo loam a ¢ lingen clay did not respond to zinc, iron an ganese (Table 1). a Grain Sorghum g Grain sorghum frequently exhibits if ficiency symptoms in the form of severe i; stunting. This condition may be correc, one or more foliar applications of ferrous I (copperas). In 1959 (Table 3), grain n did not respond significantly to soil appli of zinc, manganese and copper. a . Onions Onions grown on Harlingen clay did j spond to soil applications of copper, iron a (Tables 4 and 5). Peas Purple hull pea yields were slightly in by a soil application of zinc sulfate in 1959 3). Manganese and copper did not signi g affect yields. 1 LAY. Pounds Tons per acre Tons per acre Tons per acre Tons per acre Bagsxj Material per acre broccoli beets spinach cabbage I Check 0 1.9 12.7 6.8 13.0 Fe 138 Sequestrene 1.0 2.0 12.8 6.9 14.1 Fe 138 Sequestrene 4.0 1.9 13.1 6.7 14.5 NazZn Sequestrene 1.0 1.9 12.6 6.7 13.2 Nazln Sequestrene 4.0 1.8 12.6 7.4 13.5 Fe 330 Sequestrene 1.0 1.8 12.8 7.6 14.0 Zn 138 Sequestrene 1.0 1.9 12.9 7.3 13.3 N.S. N.S. N.S. ‘ N.S. Beets—Detroit Dark Red Spinach—-Hybrid 7 Varieties BroccoIi—Waltham 29 6 Cabbage—Globe YR Onions—L36 Yellow VEFFECT OF DIFFERENT KINDS AND RATES OF CHELATED LS ON THE YIELD AND QUALITY OF CARROTS (IM- ETY) GROWN IN A HARLINGEN CLAY SOIL IN 1962 TABLE 8. THE EFFECT OF FOLIAR APPLICATIONS OF SEVERAL MICRONUTRIENTS ON THE YIELD OF COTTON GROWN ON A HARLINGEN CLAY SOIL IN 1962 U.S. No. U.S. No. Culls, Rate” Yield H Pounds 1’s, tons 2’s, tons tons pounds pounds lint per acre per acre per acre per acre Material‘ per acre per acre 5.44 5.04 7.47 Check 480 _, ne 10 6.87** 6.00** 6.70*" BQfQn 0,20 517 g trone 4.0 7.93** 4.71 * 5.96** Baron Q_4Q 515 I18 1.0 6.l3** 5.90** 6.08** Nu “on O36 49° ‘ ITO 6.49** 6.4‘|** Nu Iron j ne 1 o 5.32 4.67* 7.73 N z o 36 467 Irene 1o 6.s4** 4.96 6.66** N: z on 469 lApplied in 18 gallons water per acre. niticance at 0.05 level. nlficance at 0.01 level. 9» Red La Soda irish potatoes were 0r response to zinc, manganese and il applications 0-f zinc sulfate increas- “ of marketable potatoes over 1,000 » acre (Table 3). Manganese and cop- Qot significantly increase the» yield of iesponse of spinach to micronutrients Variable. In 1961 on a Willacy loam I h responded significantly to soil ap- 70f zinc, iron, boron, copper, molybde- gsEs-Min-El (Table 9). The following . ‘yr h grown on an adjacent area failed Q to many of the same treatments . During the 1962-63 season, spinach Harlingen clay did not respond to soil y; of iron or zinc (Table 5). rass did not respond to soil appli- i? inc, manganese and copper in the 1959 litrials (Table 3). squash grown on a Willacy fine V soil responded to both zinc and man- ONSE OF SWEET CORN (GOLDEN BANTAM VAR.) , S MICRONUTRIENTS APPLIED TO A WILLACY T FINE SANDY LOAM SOIL IN 1962 Pounds Yield, tons per acre per acre 5.6 ‘ ybclate t .75 5.5 ybdate ‘i 1 .50 6.4 “ 12 6.0 40 5 3 51.2 6 3 50 5.8 ne 25 6.2 'tato 50 6.2 ' 25 5.8 25 5.8 zTreatments began on May 11 and repeated every 10 days through July 30. ganese (Table 3). During the 1960-61 season, squash grown on Harlingen clay did not respond to soil applications of copper (Table 4). Like- wise, yields were not significantly increased by soil applications of zinc, manganese and iron in 1963 on either Hidalgo sandy loam or Harlingen clay. On the Hidalgo loam there was some indi- cation of a response to manganese (Table 1). Further confirmation of this is needed before definite conclusions can be drawn. Tomatoes Zinc deficiency symptoms in tomatoes occur frequently when growing conditions are unfavor- able. This generally occurs during prolonged periods of cold weather reculting in cold wet soils. Such symptoms generally may be corrected by foliar sprays containing zinc. In 1963, Chico tomatoes did not respond to soil applications of zinc, iron and manganese (Table 1). However, in view of the lateness of this planting and warm. temperatures during the growing season, the lack of response is not surprising. During sea- sons when growing conditions are unfavorably cool, both iron and zinc deficiency symptoms have been observed. TABLE 9. THE RESPONSE OF SPINACH (HYBRID 7 VAR.) TO VARIOUS MICRONUTRIENTS APPLIED TO A WILLACY FINE SANDY LOAM SOIL IN 1961 Yield Pounds tons Material per acre ‘ per acre ‘ Check 5' 9.75 Borate 46 ' 12 10.25 Copper oxide (50%) 20 10.50 Copper sulfate 25 10.55 Es-Min-El 50 10.80- 330 Fe Sequestrene 25 10.15 NazMn Sequestrene 25 8.95 Nu-manese (48%) 40 8.85 Manganese sulfate 80 9.90 Sodium molybdate 1 “ ‘ 11.50 N022" Sequestrene 25 9.60 Zinc Sulfate - ~ 25 10.00 L.S.D. 0.01 .60 7 TABLE 10. THE RESPONSE OF SPINACH (HYBRID 7 VAR.) TO SEVERAL MICRONUTRIENTS APPLIED TO A WILLACY FINE SANDY LOAM IN 1962 Rate Tons Material per acre per acre Check 7.50 Copper sulfate 20.0 7.53 Copper sulfate 40.0 7.25 Brown copper oxide 10.0 7.55 Brown copper oxide 20.0 6.93 Brown nOPPO oxide ' 40.0 7.23 Naaln Sequestrene 4.0 7.20 Fe 138 Sequestrene 4.0 7.50 Sodium molybdate 1.0 6.83 Borate 46 12.0 7.05 Phosphorus-zinc Interaction Research EXPERIMENTAL PROCEDURE Field Experiments All field experiments were co-nducted on a Willacy fine sandy loam near Monte Alto in the Lower Rio Grande Valley of Texas. Results of chemical analyses of soil from the plow layer of the experimental area are as follows: pH, 8.15; organic matter, 1.04%; NaHC05-extractable P, 13.0 ppm.; CaC05 equivalent, 1.10 percent; and acid-(0.1N H01) extractable Zn, 5.6 ppm. The 1958 experiment was a 4 by 3 by 2 com- plete factorial with N, P and K as variables. Four-row plots, 50 feet long, replicated 4 times were used. Nitrogen was applied at 0, 60, 120 and 180 pounds per acre. These rates were ap- plied singly and in all possible combinations. One additional treatment of 180-120-60 + 75 pounds of Es-Min-El per acre was included to determine possible response to micronutrients. Nitrogen, P205 and K20 were from NH4N05 (33.3% N), Ca(H-2PO4)2 P205) and K20). One-half of the N and all of the P and K were applied as a preplanting application on February 3. The fertilizer was applied with a continuous belt-type fertilizer distributor which banded the fertilizers about 3 inches below and to the side of the seed zone. The remainder of the N was applied as a sidedressing on April 14. Hybrid corn (Texas 30 var.) was planted on March 5 TABLE 11. THE EFFECTS OF COMBINATIOIS OF ZN AND P FERTILIZERS ON THE ZN AND P CONCENTRATION IN PLANT TISSUE ~ l and later thinned to a 12-inch spacing the row. i In the 1959 field trials, single-row pl feet long, were used. The experimental ‘ was a randomized block with 4 repli . Fertilizer treatments (Table 11) were ap’ a preplanting application on J aunary 19. \~ of fertilizer applicationand placement same as for the 1958 experiments. A g 80 pounds of N was applied to all crops 5 applications, one-half as a preplanting tr“ and the remaining half as a sidedressing ment. The Zn was from ZnS04 (36% 2' from Ca(H2P04)2 (46% P205) and N‘ NH4N05 (33.3% N). Tomatoes (Rio i? var.) were planted on Jaunary 27, beans; dergreen var.) on March 2, and field corn 30 var.), sweet corn (Golden Bantam var cotton (Deltapine var.) on March 6. Plant samples for chemical analys taken at the following stages of growth early tasseling; tomatoes, first mature beans, early pod development; and cotto‘ boll development. The youngest fully de. leaves were sampled at random from ea Leaf samples were washed in Zn-free dried at 70° C. in a forced draft oven and 1 in a Wiley mill with all steel parts. Greenhouse Experiment A, greenhouse experiment was c0 5 using Willacy fine sandy loam where P-i Zn deficiencies were first observed in fie in 1958. Treatments based on 4,000,000 ‘ of soil per acre are given in Table 12. t< glazed pots with polyethylene bags as 2 holding 8 kg. of soil, were used. The p0“ randomized and replicated 3 times. Zip deionized, water was used to reduce the bility of contamination. Fertilizer-gr- (H2P04) (46% P205) and commercig ZnS04 (36% Zn) were used in the trea A uniform level of N was applied using grade NH4N05 in deionized water. All q cept the top 21/2-inch layer was put into t, the treatments were then applied over the soil surface and then the remainder of was added. Fertilizer Tomatoes Cotton "QUINN", Zn P Zn P Zn P Zn pounds per acre ppm % PPI" % PPm % ppm Check 24.6 .34 31.8 .41 26.3 .37 24.3 120 lb. P205 16.6 .41 35.2 .48 22.5 .49 22.9 7.2 lb. Zn 26.5 .34 34.5 .38 24.4 .33 26.1 7.2 lb Zn + 120 lb. P295 25.0 .40 39.7 .43 25.2 .43 20.1 Statistical significance ** NS * NS NS NS NS *Treatment effect significance at 5% level. **Treatment effect significance at 1% level. NS Refers to no statistical significance. lbean seeds (Red Kidney var.) were ., inch deep and the- soil was wetted to “point 0f saturation. After seedling all but three plants per pot were re- ubsequently the pots were watered with j Water when approximately 50% 0f the moisture had been used. plants were grown t0 bloom stage, time the entire top o-f the plants was and prepared for laboratory analysis e procedures previously described. I Procedures 'H was determined on a saturated soil nic matter by the potassium dichro- A 0d and C3003 equivalent by acid neu- ___(21). NaHCOg-extractable P was de- by the method described by Olsen (18). y extracted with 0.1N HCl (17), and Zn ‘g ined on the acid extract by the official hizone method (2). ‘determinations on plant material were perchloric-nitric acid digests using the rAC dithizone procedure (2). Total P ined by the vanadomolybdate method SULTS AND DISCUSSIONS Experiment wet soils for several weeks after plant- v -» in extremely slow growth of the corn. . f within 3 or 4 weeks after plant emer- outstanding growth response was noted 7th a fertilizer treatment of 180-120-60 Qunds of Es-Min-El per acre. On the v» severe chlorosis and stunting of plants in all plots that received P fertilize-r. gfertilized with P was normal in color i» as large nor as advanced in maturity receiving a complete fertilizer plus Yfents. The deficiency symptoms were the “white bud” symptoms of Zn de- scribed by Barnette and coworkers (3, spected Zn deficiency was confirmed gr sprays o-f ZnSO4 corrected the chlo- ie Zn deficiency was evident through he growing season; however, plants (stunted early in the season resumed f d attained normal size as warmer . me. 'eld of shelled corn was reduced on an v.1 and 41.1% respectively, fro-m the _ of 60 and 120 pounds o-f P205 per ‘is interestinghto note that yields were ed by the treatment containing 120 g P205 plus 75 pounds per acre of Es- 0% ZnSO4) (Table 13). Yield re- ere mainly a result of small, poorly- i‘: caused by a delay in silking until 1- shed. This has also been reported d Gallo (13) and by Lingle and Holm- TABLE 12. THE EFFECT OF P AND Zn FERTILIZER ON THE AVERAGE GROWTH AND NUTRIENT ABSORPTION BY BEANS (RED KIDNEY VAR.) GROWN ON A WILLACY FINE SANDY LOAM Oven dry Petiole weight Total Total P205 Zn length per pot Zn P Pounds Pounds per acre per acre cm. g. ug. mg. 0 0 11.7 12.0 430 39.3 100 0 8.1 10.7 235 56.1 200 0 8.0 10.7 215 69.2 400 0 9.7 12.0 247 92.5 800 0 8.9 13.0 359 117.0 I600 0 8.7 13.7 295 137.0 0 9.0 _12.8 13.7 740 41.1 400 9.0 12.5 15.0 241 57.3 Statistical significance P ** ** ** ** 1n ** =|==|= =|= =H= Zn X P * NS ** ** *Treatment effect significant at 5% level. **Treatment effect significant at 1% level. NS Refers to no statistical significance. Corn yields were also affected by a signifi- cant N X P interaction. Without P, corn yields tended to increase with increasing rates of N; however, as the level of P was increased the yields decreased with increasing rates of N. Nitrogen and K did not significantly affect yields (Table-13). Nelson et al. (17) using acid-extractable Zn and “titratable alkalinity” values have devised a method for distinguishing between Zn-deficient and Zn-nondeficient soils for field crops. Based on this proposed method, the Willacy soil used in this experiment, which has a “titratable alka- linity” value of 22.0 and an acid-extractable Zn content of 5.6 ppm, would be considered nonde- ficient. The “titratable- alkalinity” value of 22.0 may seem somewhat high as Willacy fine sandy loam is generally considered a noncalcareous soil. This is no doubt due to heterogeneous soil con- ditions of the experimental area possibly as a result of land-leveling operations several years preceding the 1958 experiment or from the pres- ence of other alkaline materials. On the basis of the outstanding growth re- sponse- to Es-Min-El, the lack of deficiency symp- toms in plots not receiving P fertilizers, and the severe Zn-deficiency symptoms induced by P TABLE 13. THE EFFECT OF N AND P FERTILIZERS ON THE YIELD OF TEXAS 30 FIELD CORNi P205 Pounds of N per acre per acre 0 60 120 180 Averages Bushels of shelled corn per acre 0 79.4 88.3 89.7 89.9 86.8 60 60.4 57.3 65.8 62.4 61.5 120 69.0 49.1 41.7 44.6 51.1 Averages 69.6 64.9 65.7 65.6 Statistical significance: P, 1% level; N x P, 5% level ‘The treatment 180-120-60 + 75 lb. Es-Min-El/acre produced an average of 93.9 bushels per acre. Figure ‘I. Red Kidney bean plants showing necrotic areas on lower cotyledonary leaves. Necrotic areas occurred as a result of P fertilization. fertilization, this soil may be borderline with respect to being deficient 0r nondeficient in Zn. If this is the case then the cold, wet soil condi- tions at planting time and the several Weeks that followed could very wellehave contributed to the expression of the Zn deficiency symptoms and response through the effect of such conditions on root development and retarded growth. In such a borderline soil with respect to available Zn and under the unfavorable» soil conditions that existed, it is possible that the banding of Ca(H2PO4)2 affected the availability of Zn in a localized zone to such an extent that sufficient Zn was not absorbed by the limited root system of the corn plants early in the» season for normal growth. 195.9 Field Experiments Zinc-deficiency symptoms were noted in both sweet and field corn where P fertilizer alone was applied. These symptoms, however, were not as acute as those observed the year before. This was probably a result of more favorable growing conditions early in the growing season under which more extensive root growth was possible. Deficiency symptoms were not present in beans and cotton. Mild Zn-deficiency symptoms oc- curred in tomatoes where P fertilizer alone was applied. a The concentration of Zn and P in the young- est mature leaves of tomatoes, field corn, cotton and beans is given in Table 11. Since total plant yields were not taken, total absorption values for Zn and P cannot be presented. In tomatoes where plants were not stunted but mild Zn-de- ficiency symptoms occurred, the concentration of Zn in the leaf tissue was reduced from 24.6 ppm in checks to 16.6 ppm in plants fertilized with P fertilizer. On the other hand, in field corn where plants were stunted, the Zn concentration in Zn-deficient plants was higher. The higher concentration of an element within the tissue of 19 Figure 2. Red Kidney bean plant showing Zn symptoms. Note elongated leaves with leaf margins curli " and the compact-type plant as a result of shortened leaf’ a plant deficient in that element is known “Steenbjerg effect” (19) and has been a by other workers (12). In most cases the tent of plants was slightly higher when lizer was applied. l Greenhouse Experiment Results from a greenhouse experiment I the Willacy soil further confirm that Z, ciencies in some crops may be induced by = . lization. Results are given in Table 12. I Zinc-deficiency symptoms in bean i’ were observed at every level of P fertili weeks after planting. Bean plants in were mildly chlorotic, but acute deficiency ‘ toms did not occur. Plants growing g treated with 9.0 pounds of Zn per acre wer. green in color indicating some response s; Those in soil treated with both Zn and . mildly chlorotic with necrotic areas occu a the cotyledonary leaves (Figure 1). I stunting of the plants did not occur. i The Zn-deficient plants were mildly c and the trifoliate leaves were more e10, than normal with the leaf margins curl wards (Figure 2). Grayish-brown to t_ colored spots occurred in the interveinal ., some of the leaves. Necrotic areas were on the cotyledonary leaves of every plant‘ in soil treated with P. Beans fertilized 2 alone had shorter leaf petioles (Table 12) resulted in a more compact and bushy plan condition was not evident when Zn and p; applied together or when Zn was appliedqi Shortened petioles and internodes are , associated with a Zn deficiency in plants Phosphorus treatments significantly a the yield of oven-dry plant material bu rather unusual way. The first two level, caused significant reductions in yield. plant material grown in soil treated wig iof P205 per acre was the same as for the