1 Area-specific fertilizer recommendations for hybrid maize grown by Malawian smallholders A Manual for Field Assistants by Action Group I * Maize Productivity Task Force written by Todd Benson Maize Commodity Team - Chitedze Agricultural Research Station and member of Action Group I, Maize Productivity Task Force August 1999 In 1997 preliminary area-specific fertilizer recommendations were given to all Extension Field Assistants as part of their training for the nationwide 1997/98 Maize Fertilizer Recommendations Demonstration. This Demonstration was successfully implemented, and the results were used to assess the value of the preliminary fertilizer recommendations. As a result of this assessment, changes have been made to the recommendations so that they will be easier for farmers to use. These new recommendations presented here are the ones which you will be using with farmers for the foreseeable future and represent the end of the work of Action Group I of the Maize Productivity Task Force on developing area-specific recommendations. This manual presents the new recommendations along with necessary information on how to make use of them with farmers growing hybrid maize. There are two principal changes to the area-specific recommendations relative to those which you were given in 1997: 1) General soil texture no longer appears as a consideration in the base recommendations. However, separate recommendations are still provided for the two different production aims of the farmer. Consequently, rather than four possible fertilizer recommendations for an Extension Planning Area (EPA), now there are only two. 2) Rates of application have been revised for some EPAs. It might have been expected that all these recommendations would consist of is a map or table showing the fertilizer recommendation that applies in each EPA of the country. Unfortunately the rapid economic changes which are currently taking place in Malawi mean that the recommendations must be more than that. The economic conditions of today will not be the same as we experience next year. Consequently, the optimal rates the most profitable rates of fertilizer for farmers to use this year will not necessarily be the right ones for farmers to use next year. This document does present two basic area-specific fertilizer recommendations for * The members of Action Group I during the period these recommendations were developed were J.D.T. Kumwenda (chairman), K.M. Chavula, A.D.C. Chilimba, A.C. Conroy, R.A. Gilbert, A. Gomez, R.B. Jones, V.H. Kabambe, the late E.E. Kanyenda, S.K. Mughogho, B.J. Sizilande, and T.D. Benson.
2 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 2 each EPA, but it then goes on to provide you with knowledge and tools to use in modifying these recommendations to make them more appropriate for the particular circumstances farmers might face in your area. Thus this manual is much more than simply recommended rates of fertilizer application for maize. The manual is divided into the following sections: WHY AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR HYBRID MAIZE?...2 FERTILIZER RECOMMENDATIONS DECISION TREE...3 ECONOMICS AND APPROPRIATE FERTILIZER APPLICATION...5 THE PRICES USED FOR MAIZE AND FERTILIZER IN DEVELOPING THE RECOMMENDATIONS...8 THE BASIC AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR HYBRID MAIZE...11 USING CREDIT OR USING ONES OWN CASH FOR ACQUIRING FERTILIZER...14 HOW FARMERS CAN MAKE THE BEST USE OF THEIR FERTILIZER ON MAIZE...15 HOW TO APPLY THE PROPER AMOUNT OF FERTILIZER TO MAIZE...21 HYBRID SEED OR LOCAL SEED?...22 CLOSING REMARKS...24 APPENDIX PATTERN OF AREA-SPECIFIC FERTILIZER RECOMMENDATIONS WITHIN ADDS...25 Why area-specific fertilizer recommendations for hybrid maize? In the 1980s many farmers in Malawi began to grow hybrid maize using fertilizer. Field Assistants advised farmers throughout the country that they should apply 87 kg of Di-ammonium Phosphate (DAP) fertilizer and 175 kg of urea fertilizer per hectare of hybrid maize. This rate provides the crop with 96 kg of nitrogen and 40 kg of phosphate per hectare. Several problems with this blanket recommendation were recognized by farmers, extension officers, and agricultural scientists: Malawi is a diverse country in climate and in soils. The blanket recommendation does not recognize this. The amount of extra maize which farmers receive from applying fertilizer differs from place to place depending on the rainfall received and the soil upon which the maize is grown. For example, one should not expect that a fertilizer rate appropriate for farmers growing maize near Kasungu would also be suitable for those growing maize near Balaka. The environments in the two areas are very different neither the rainfall patterns nor the soils are the same. Different fertilizer recommendations should apply to each area. The rates given in the blanket recommendation are not profitable for many farmers to use. In many areas of the country the cash from the sale of the additional maize which farmers received from using fertilizer at the old recommended rate was not enough to repay the credit used in buying the fertilizer. Once the fertilizer credit was repaid, little additional maize was left for the farmer s own use. Many farmers found that lower rates of fertilizer application were more profitable. In recent years as prices of fertilizer have doubled or tripled, the recommended blanket rate has become even less profitable.
3 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 3 Agronomically, the nutrients in the blanket recommendation are not well balanced. Nitrogen is the most important nutrient required by maize. The emphasis in the blanket recommendation on nitrogen is appropriate. The problem is that for many areas of the country the rate recommended is too high. However, maize in most areas of Malawi does not benefit from rates of phosphate above 20 kg/ha. Lower rates than the 40 kg/ha recommended are more appropriate. Moreover, sulphur is not provided in the blanket recommendation of DAP and urea. Maize in Malawi requires some sulphur for optimal growth. Out of the work of Extension Field Assistants in implementing the nationwide 1995/96 Fertilizer Verification Trial and the 1997/98 Maize Fertilizer Recommendations Demonstration, area-specific recommendations have now been developed and approved by the Ministry of Agriculture and Irrigation. The basic area-specific recommendations are presented in maps and tables later in this manual. However it is very important to realize that the recommendations as shown in the maps are only the starting point. For many farmers the basic area-specific recommendations will be no better for their particular circumstances than was the blanket fertilizer recommendation. Of equal importance to the farmer using the recommendations is how to modify them to suit their particular needs and to provide maximum benefit to his or her household. The manual provides guidelines as to how the recommendations should be modified to make them worthwhile for a particular farmer, farming in a specific area, with particular resource constraints, and facing different and often changing prices for fertilizer and maize. Fertilizer recommendations decision tree The decision tree diagram in Figure 1 shows how the appropriate fertilizer recommendation for a farmer is determined. In contrast to the blanket recommendation which these area-specific recommendations replace, a maize field in Malawi does not have only one rate of fertilizer applicable. Rather, two recommended rates are offered. The one a farmer chooses depends on why the farmer is producing maize. In order to use the basic area-specific fertilizer recommendations, a farmer needs to know two things: 1) The EPA in which the farmer is growing the maize. The area-specific recommendations apply to Extension Planning Areas or to larger agricultural extension districts Rural Development Projects (RDP) or Agricultural Development Divisions (ADD). Consequently, the farmer needs to know in which EPA he or she is farming. Location is important when considering fertilizer use: Where one is in Malawi determines what sort of weather and general soil conditions the farmer should expect.
4 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 4 Figure 1: Decision tree underlying the recommendations EPA? Start Production aim? For Home Consumption For Market Sale Recommendation Recommendation 2) The production aim of the farmer. The production aim of the farmer is either for home consumption and use or for sale at the market. The farmer places a different value on the maize depending on what is the intended use of the maize. If producing for the market, a reasonable value for the maize is the producer price which the farmer will receive in the market. However, if the farmer is producing for home use, the significantly higher consumer maize price is the value of the maize, as every kg of maize the farmer produces in his or her own field is one less that will have to be purchased in the market at the consumer maize price and transported back home. As this price is considerably higher than the producer price, it makes economic sense for the farmer to apply higher rates of fertilizer to the maize when producing for home consumption. As will be seen, the recommendations reflect this. The economic reasons for why two different recommendations result from the two prices will be given in the next section. However, many farmers will be producing both for market sale and for home consumption. The recommendations presented here are maximum fertilizer application rates when producing purely for either of the two aims. For mixed production where some maize from the field goes for home consumption and some for market sale, a reasonable fertilizer level between the two recommendations for a particular field should be used. With these two pieces of information, one can determine the appropriate basic fertilizer recommendation for the farmer to use on his or her hybrid maize. Basic is underlined because figuring out the best recommendation for a farmer does not end with the maps. The basic recommendation from the maps should be evaluated in light of two important factors: 1) The fertilizer to maize price-ratio in the area. Is it higher, lower, or the same as that which was used to develop the basic area-specific fertilizer recommendations? As will be discussed, the basic recommendation should be adjusted if it is not the same.
5 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 5 2) The amount of cash the farmer has. Can she or he afford the entire recommended fertilizer package with cash on hand or credit? If not, how should the available cash of the farmer be used on fertilizer? Economics and appropriate fertilizer application Determining which rates of fertilizer should be recommended for maize in a particular area is not accomplished using some sort of magic or difficult scientific processes. Rather, the common sense approach is followed of making sure that the net benefits which the farming household will enjoy from the use of fertilizer will be the highest possible. The net benefit is the value of the maize produced after you have subtracted the cost of the fertilizer: Net benefit = ([bags of maize harvested] x [price of maize per bag]) - cost of fertilizer The level of the net benefits which a household achieves are determined by: the conditions under which the fertilized maize was grown, the cost of fertilizer, the value of maize for the household. As such, fertilizer recommendations are derived by a combination of agronomy and economics. The agronomic aspect lies in the response in maize yield to fertilizer. That is, if I put one kg of fertilizer on my maize, how many additional kg of maize would I receive? The level of the response is determined by a wide range of factors. The most important, however, are the condition of the soil, particularly its natural fertility; the weather conditions of the particular growing season; and the management of the maize by the farmer adequate weeding, early planting, timely fertilizer application, and so on. An important aspect of the response of maize to fertilizer is that the level of response declines as more fertilizer is applied to the maize. This is an example of the law of diminishing returns. The law of diminishing returns can be portrayed in two ways using the average maize yields from the 1995/96 Fertilizer Verification Trial from across the country. First, Figure 2 is the graph of average maize yields per hectare across the country for the treatments of the Trial where: i) no fertilizer was applied; ii) 100 kg/ha of fertilizer was applied, iii) 200 kg of fertilizer was applied; and iv) 250 kg of fertilizer was applied. If the law of diminishing returns did not apply, the line should be straight. However, it is not straight, but it curves downwards. This means that for every additional amount of fertilizer you apply, you get less maize yield for that fertilizer than what you received at lower rates of application. The greatest response in maize yield to fertilizer occurs at the lowest rates of fertilizer application.
6 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 6 Figure 2: Average yields of Fertilizer Verification Trial and the law of diminishing returns Maize yield (kg/ha) Fertilizer (kg/ha) Secondly, the right column in Table 1 shows the average maize yield which was received in the Verification Trial per kg of fertilizer applied at different rates. The way these numbers are calculated is by taking the maize yield for a particular fertilizer application level and subtracting the maize yield when no fertilizer is applied (0 kg/ha). * The result is then divided by the rate of fertilizer applied. For example, at 200 kg/ha, the kg increase in maize yield per kg of fertilizer applied is ( ) 200 = = 7.4. Again, if the law of diminishing returns did not apply, the numbers in the column to the right would all be the same. However, they become smaller as the rate increases. If one extends the trend, agronomically this means that at some higher level of application, no additional maize yield will result from adding fertilizer. As a consequence of this agronomic feature of fertilizer use, economically there will also be a rate of fertilizer application, much lower than the agronomic maximum level, where no additional net benefit will result from applying more fertilizer. This rate is where the value to the farmer of any additional maize produced will be less than the cost of any additional fertilizer applied to the maize. It is this level of fertilizer application which should be the maximum rate recommended for farmers. The recommended rate of fertilizer application, consequently, is determined to a large Table 1: The law of diminishing returns in fertilizer application to maize fertilizer application level average maize yield (kg/ha) average kg increase in maize yield per kg fertilizer applied 0 kg/ha kg/ha (50 kg 23:21:0+4S & 50 kg urea) kg/ha (100 kg 23:21:0+4S & 100 kg urea) kg/ha (100 kg 23:21:0+4S & 150 kg urea) * It is important to realize that these yields are average yields and reflect very good management of the maize. Particularly for the upland areas of Malawi where most of the maize is grown in the country, the yields which farmers should expect when no fertilizer is applied will be considerably lower than that shown here
7 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 7 degree by the cost of the fertilizer used and the value of the maize for the farmer usually the price of maize at the market. For example, if the price of fertilizer is very high while the price of maize is very low, then only very low levels of fertilizer use can be profitable. In a situation of extremely high fertilizer prices and low maize prices, as might happen following a year with a very good maize harvest, it might well be wiser for the farmer not to use fertilizer, but to take the money which could be spent on fertilizer for maize and purchase grain instead. Fundamentally, it is the ratio of the price of fertilizer to the price of maize which determines the optimum level of fertilizer application for a farmer. This ratio is the price of fertilizer per bag (for example, urea) divided by the price of maize per bag, both bags being the same weight. If prices change, and the ratio of the price of fertilizer to the price of maize no longer is what it was when the fertilizer recommendations originally were made, then the optimal level of fertilizer application will also have changed and the fertilizer recommendations should change. The relationship between the direction in which the price-ratio changes and the direction in which the optimal fertilizer application rate should change is an inverse relationship. This means: If the fertilizer to maize price-ratio goes up, the recommended level of fertilizer application will be lower than previously. If the fertilizer to maize price-ratio goes down, the recommended rate of application will be higher. You might ask, What does all of this economics have to do with the new area-specific fertilizer recommendations? It has been presented principally for three reasons: 1) The basic area-specific fertilizer recommendations presented later in this document were derived in a manner similar to that sketched out here. In essence, net benefits were calculated from the maize yields resulting from the four rates of fertilizer applied in both the 1995/96 Fertilizer Verification Trial and the 1997/98 Maize Fertilizer Recommendations Demonstration. That fertilizer rate which gave the greatest net benefit for fields in a particular zone was judged to be the appropriate recommendation. 2) The decision tree upon which the area-specific recommendations are based uses two different values for maize the producer price and the consumer price which correspond to the two production aims a farmer might choose. Consequently, two different fertilizer to maize price-ratios are used and, subsequently, two different optimal rates of fertilizer application result one which is applicable when the farmer values the
8 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 8 maize for its use in home consumption, and a second when it is valued at the price it will fetch when sold at the market. 3) Prices for maize and fertilizer in Malawi will continue to change in the future, just as they have in the past, so optimal rates of fertilizer application on maize will change frequently as well. This is the most important reason why all extension officers and farmers should understand how the economics of fertilizer use determine the rate one should apply. In order to provide good fertilizer recommendations to farmers, extension officers must have an understanding of how changing price-ratios for fertilizer and maize change the optimal level of fertilizer application on maize in a recommendation zone. In order to use these recommendations effectively, one must be aware of the fertilizer to maize price-ratios upon which the area-specific fertilizer recommendations were developed. These are given in the next section. Knowing these, extension officers and farmers should then calculate the price-ratios for their area, compare them to those used to develop the recommendations, and change the recommendations as is appropriate. The prices used for maize and fertilizer in developing the recommendations Price changes will mean different optimal recommendation levels depending upon how the maize and fertilizer prices change relative to each other. Paying attention to the changes in the ratio of the price of fertilizer to the price of maize is the key thing. (Remember, the priceratio is the price of fertilizer divided by the price of maize.) For example: If both maize prices and fertilizer prices rise or fall by equal proportions or percentages, the price-ratio will stay the same. The recommendations which were appropriate before still will remain appropriate. A lower price-ratio than that upon which the recommendations are based means that higher rates of fertilizer can be used. Lower price-ratios can result from: Maize prices rise without the fertilizer price changing. Maize prices stay the same, but fertilizer prices fall. Fertilizer prices rise, but maize prices also rise and by a greater proportion. Maize prices rise, and fertilizer prices fall. And so on. A higher price-ratio means that lower rates of fertilizer than were previously applied should be used. Higher price-ratios also can come about in many ways: Fertilizer prices rise, while maize prices do not rise by the same proportion. Maize prices drop, while fertilizer prices stay the same. Fertilizer prices rise, while the price of maize does not. And so on.
9 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 9 If the actual fertilizer to maize price-ratio in your area is significantly different from the price-ratios used to calculate the basic recommendations, you should adjust the basic recommendation for your area to make it more appropriate. Prices used for the recommendations for home consumption production aim The home consumption recommendations were calculated based upon the prices for urea and 23:21:0+4S fertilizers and the consumer price of maize. The consumer price is that price which you pay when you go to the market to buy a bag of maize for your own use not the price which merchants will give you when they buy maize you harvested. The prices used in calculating the recommendations which apply when the production aim is for home consumption were as follows: consumer price of maize: MK per 50 kg bag urea: MK per 50 kg bag 23:21:0+4S: MK per 50 kg bag The easiest way to keep track of the fertilizer to maize price-ratio is to use urea as a general indicator of fertilizer prices. In general the price of 23:21:0+4S and other fertilizer should change in a similar manner to the price of urea. The price of 23:21:0+4S is shown here simply for later reference. The urea to maize price-ratio used to develop the for home consumption fertilizer recommendations was MK 840 MK = 2.3. If you find that the price-ratio in your area is significantly different than this ratio, the rate of fertilizer which you use or which you advise farmers to use should be changed from the basic rates recommended. As a rough guide to determine whether the difference in price-ratio is significant or not, if the difference is over 15 percent, consider adjusting the fertilizer application rates. That is, you should use somewhat less fertilizer than the basic recommendation if the ureato-maize price-ratio is above 2.6. More can be used if the price-ratio is less than 2.0. How much less fertilizer should be applied under higher price-ratios depends on how high the price-ratio in your area is relative to that used to develop the recommendation. If the difference is 15 percent higher, consider the next smaller package of fertilizer. For example, if the basic recommendation is 69:21:0+4S, use 35:10:0+2S instead.
10 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 10 Prices used for the recommendations for market sale production aim The market sale recommendations were calculated based upon the fertilizer prices and the producer price of maize. The producer price is that price which merchants will give you when they buy the maize you harvested and have brought to market. In determining what rate of fertilizer should apply when one will be selling the maize at the market, the fertilizer prices remained the same as above. However, the maize price used was MK per 50 kg bag. The urea to maize price-ratio used to develop the for market sale fertilizer recommendations was MK MK = 3.2. Again, use 15 percent in determining whether the difference in price-ratio is significant or not. That is, you can use somewhat more fertilizer than the basic recommendation when producing for the market if the price-ratio is less than 2.7. Less should be used if the price-ratio is more than 3.7. In fact, once the price-ratio rises above 4.0, rarely can fertilizer use be recommended for most farmers growing maize for sale. Estimated future maize prices should be used Realize that the maize price which should be used in making the calculation of the priceratio is not the current price of maize, but the price after the harvest which you and the farmer expect. It is that price which determines whether or not the use of fertilizer on the growing maize was a wise and profitable thing to do. As no one knows before the rains come what maize prices will be like after the harvest, the best you can do is estimate this maize price. However, in estimating maize prices, remember that maize prices change as time passes from the harvest. Prices are lowest immediately after harvest, but can be very high just before the next harvest. Which price should be used? Use an estimate of what you expect the maize price will be at the time after harvest when the farmer typically sells or buys maize in the market. For example, if he will be producing for the market and will need to repay a loan immediately after harvest, then use as an estimate the low producer price common at that time. Finally, different merchants offer different prices in the market. ADMARC gives one; large, full-time traders give another; and small, part-time traders give others. Whose prices should you base your estimates upon? Use those of the merchant with whom the farmer would typically deal. For many farmers, if they buy or sell in small quantities, they will not receive the relatively good prices which ADMARC or large traders will offer, but must be content with the lower producer prices or higher consumer prices of the small, part-time traders.
11 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 11 The basic area-specific fertilizer recommendations for hybrid maize The recommendations are presented in list form by Agricultural Development Division (ADD) and Rural Development Project (RDP) in Table 2 and in maps in Figure 3. The recommendations are based upon four rates of fertilizer: nil; 35:10:0+2S; 69:21:0+4S; and 92:21:0+4S. These numbers correspond respectively to the kilograms of nitrogen : phosphate : potassium + sulphur (S) applied per hectare in the fertilizer. The rates are based upon the use of the fertilizers 23:21:0+4S and urea (46% nitrogen). As shown in Table 3, the rate 35:10:0+2S corresponds to the application of one bag of Table 2: Area-specific fertilizer recommendations, by ADD, RDP, and EPA Market Sale Home Consumption ADD RDP EPA Recommendation Recommendation Karonga Chitipa All, except Misuku 35:10:0+2S 69:21:0+4S Mzuzu Misuku Nil 69:21:0+4S Karonga All Nil 35:10:0+2S Rumphi North Mzimba Mpherembe, Bwengu, Zombwe, Bolero 35:10:0+2S 92:21:0+4S Muhuju, Nchenachena/Phoka Nil 69:21:0+4S Central Mzimba All 35:10:0+2S 92:21:0+4S South Mzimba All 35:10:0+2S 92:21:0+4S Nkhata Bay All, except Mpamba Nil 35:10:0+2S Mpamba Nil 69:21:0+4S Kasungu All All 35:10:0+2S 92:21:0+4S Lilongwe All All 35:10:0+2S 92:21:0+4S Salima Salima All 35:10:0+2S 92:21:0+4S Nkhotakota Nkhunga, Linga Nil 69:21:0+4S Zidyana, Mwansambo 35:10:0+2S 92:21:0+4S Bwanje All 35:10:0+2S 92:21:0+4S Machinga Mangochi All 35:10:0+2S 69:21:0+4S Namwera All 35:10:0+2S 69:21:0+4S Balaka Ulongwe, Mpilisi 35:10:0+2S 69:21:0+4S Bazale, Phalula, Rivi-rivi 35:10:0+2S 92:21:0+4S Kawinga All 35:10:0+2S 69:21:0+4S Zomba All, except Mtubwi, Chingale 35:10:0+2S 92:21:0+4S Mtubwi, Chingale 35:10:0+2S 69:21:0+4S Blantyre Shire Highlands All, except Lirangwe 35:10:0+2S 92:21:0+4S Lirangwe 35:10:0+2S 69:21:0+4S Thyolo All 35:10:0+2S 92:21:0+4S Mulanje All 35:10:0+2S 92:21:0+4S Phalombe All 35:10:0+2S 92:21:0+4S Mwanza All 35:10:0+2S 69:21:0+4S Shire Valley All All Nil 35:10:0+2S
12 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 12 Figure 3: Area-specific fertilizer recommendations for hybrid maize grown by smallholders Recommended per ha application rates nil 35:10:0+2S 69:21:0+4S 92:21:0+4S 35:10:0+2S = 1 bag of 23:21:0+4S 1 bag of urea per hectare. 69:21:0+4S = 2 bags of 23:21:0+4S 2 bags of urea per hectare. 69:21:0+4S = 2 bags of 23:21:0+4S 3 bags of urea per hectare. (50 kg bags of fertilizer) Unshaded areas are nonagricultural lakes, cities, forest reserves, or national parks. Boundaries of the ADDs are shown. Market Sale production aim Home Consumption production aim 23:21:0+4S and one bag of urea per hectare, while 69:21:0+4S results from applying two bags of each, and 92:21:0+4S is the amount of nutrients applied from two bags of 23:21:0+4S and three bags of urea per hectare. The most common recommendation if producing for home consumption is 92:21:0+4S, while 35:10:0+2S is the general recommendation when growing maize for the market. When the two maps of Figure 3 are combined into one map, four separate sets of the two production aim recommendations are required to cover all areas of the country, as is shown in Figure 4. The image is rather complex when examined at the national scale. However, when you look at it at the level of the Agricultural Development Division (ADD) or the even smaller RDP, the pattern is considerably simplified. Of the thirty-one RDPs in Malawi, only seven of them have been assigned more than one set of recommendations. Moreover, the complexity in the recommendation pattern for these few RDPs usually is because they cover two or more
13 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 13 Figure 4: Area-specific fertilizer recommendation zones of Malawi Recommendations by production aim Market Sale nil Home Consumption 35:10:0+2S nil 35:10:0+2S 35:10:0+2S 69:21:0+4S 69:21:0+4S 92:21:0+4S Fertilizer recommendations for hybrid maize in kg of N:P 2 O 5 :K+S per hectare. Unshaded areas are non-agricultural. ADD boundaries shown. ecological zones which have different fertilizer response patterns. As most extension officers operate within the section or the EPA, you should find the recommendation scheme to be sufficiently simple. Note that these rates are maximums, rather than all-or-nothing recommendations. Lower rates of fertilizer than those recommended will provide the farmer with good returns in maize yield or income. Application rates up to the levels indicated in all but the worst years will provide the farmer with an attractive return. Field Assistants should advise farmers, particularly when producing for home consumption, that a little fertilizer is a worthwhile addition to the maize crop, even if not applied at the maximum level recommended.
14 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 14 Table 3: Fertilizers of recommendations Recommendation 35:10:0+2S Bags of fertilizer per hectare 23:21 :0+4S 50 kg & Urea 50 kg However, higher rates of application place the farmer at considerable risk of losing money on the use of fertilizer, particularly when weather conditions are poor. In this light, the most interesting parts of the maps in Figure 3 are particularly where lower rates of fertilizer are recommended. 69:21:0+4S 92:21:0+4S 23:21 :0+4S 50 kg Urea 50 kg 23:21 :0+4S 50 kg & & 23:21 :0+4S 50 kg Urea 50 kg 23:21 :0+4S 50 kg It is important to note that these recommendations are generalizations. They assume a single ecological zone in each EPA. Several EPAs in Malawi have two or more ecological zones in which maize is grown. The Appendix highlights where in particular EPAs modifications to these recommendations should be made based on variability in growing conditions within EPAs. Urea 50 kg Urea 50 kg Urea 50 kg Using credit or using ones own cash for acquiring fertilizer The price that one pays for fertilizer is not the only cost which a farmer faces when using fertilizer. The most important of these other costs is that of credit how the farmer acquires sufficient cash to pay for the fertilizer in the first place. The two different production aims have significantly different credit costs. First, if the farmer is producing for the market, it is assumed that the farmer expects that the maize produced will pay fully for all costs, including the cost of acquiring the cash to purchase the fertilizer that is, the cost of credit. Consequently, it is very important to bear in mind when using these recommendations that if the farmer is producing maize using fertilizer acquired through commercial credit (MRFC or the like), then the market production recommendations must be used. Those recommendations incorporate the full costs of this credit in determining the level of fertilizer to apply. The home consumption recommendations do not. Unfortunately, it is very likely that the farmer using credit will not be able to pay back the loan if he or she uses higher rates of fertilizer than those given under the market production production aim. If annual credit interest rates for farmers rise significantly, this will increase the total cost of the fertilizer, and increase the fertilizer to maize price-ratio. If credit rates rise above 50 percent, then farmers should apply lower rates than recommended in the market production basic
15 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 15 recommendations. However, as noted above, at higher price-ratios, it is unlikely to be profitable for farmers to apply fertilizer to maize which is to be sold at the market. Secondly, if the farmer is producing maize with fertilizer for home consumption, it is assumed that the cash for purchasing the fertilizer did not come from commercial credit. Rather, the farmer acquired the money from another cash-producing activity of the household. This most commonly would be from tobacco or cotton production, but could also be from wage labour and ganyu, cash gifts from family members working in urban areas, or some other source. The cash used for the fertilizer is not being treated as an investment from which a profitable return will be produced. Rather, it is being consumed for household welfare, after first using it for fertilizer to acquire in the end considerably more maize than could be directly purchased with the money. However, extension officers particularly should be clear about the difficulties of purchasing fertilizer with ones own cash. Field Assistants and other extension officers are paid a salary from which they can purchase fertilizer. Their civil service position is the cashproducing activity noted above from which the fertilizer is purchased when it is to be used to produce maize for home consumption. However, for most rural households, where does this money come from? Unless they grow a cash crop, most farmers are unable to accumulate the money required to purchase the amount of fertilizer recommended for the home consumption production aim. Many households will have few cash-producing options beyond ganyu, which in itself may be insufficient to allow the household to meet all of its other cash needs and buy fertilizer as well. That said, remember that the recommendations noted in the basic recommendation maps should be seen as maximums. Even if farmers are unable to put the recommended amount on their maize, smaller amounts of fertilizer will provide them with a good return. Farmers should be encouraged to put on the amount of fertilizer which they can afford. In summary, changes in credit costs should be considered when developing an appropriate fertilizer recommendation for maize being grown for market sale, particularly if the interest rates charged by rural credit lenders rise above 50 percent. However, for production of fertilized maize for own household use, the cost of credit is irrelevant so long as one recognizes that the cash to buy the fertilizer must come from some other cash-producing activity of the household, and not credit. How farmers can make the best use of their fertilizer on maize Fertilizer is much more expensive now than it was in the 1980s and early 1990s. Farmers who regularly were able to afford to apply recommended rates of fertilizer in the past are no longer able to do so. Yet, farmers recognize that fertilizer helps them achieve the maize
16 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 16 yields they require to feed their families. They need to be confident in how they can make the best use of whatever amount of fertilizer they can afford. What follows are a few guidelines. Good farming practices Regardless of how much or how little fertilizer farmers are able to use on their maize, they must do a good job in growing the maize. This means early planting, on-time application of fertilizer, and, most importantly, good weeding. These points are emphasized to farmers over and over again, but they remain a critical aspect of fertilizer use. Plant early. To maximize the returns in maize yield to expensive fertilizer, make sure that the crop to be fertilized is planted on time with the first good rains. Any delays in planting mean lower harvests. Fertilizer must be applied properly and on time. The basal application of 23:21:0+4S fertilizer is best applied before planting. However, as most farmers are not willing to apply fertilizer until they first see the maize plants emerge, inform them that it must be put on immediately after emergence. When the maize is young is when it needs the phosphate that is applied in the basal fertilizer. The top-dressing of urea should be applied three to four weeks after the basal dressing. Do not delay more than that. The later the top-dressing is applied, the more the nitrogen in the fertilizer goes into the leaves and stalk of the plant, rather than into the grain. Particularly with urea, be careful that the fertilizer is not placed in contact with the maize seedling. Urea can burn the seedling, possibly even killing it. It should be placed about 10 cm away from the plant. Urea should also be covered with soil after application. Otherwise, some of the nitrogen in the urea will be lost to the air. Two good weedings should be done on the maize. The first should be done as soon as the first weeds appear, within three weeks after planting. The second weeding should be done three to four weeks later. It makes sense to weed well when using fertilizer: Why fertilize weeds? Rather than putting on a lot of fertilizer and weeding poorly, a farmer would be wiser to put on less fertilizer and use the money saved on fertilizer to hire ganyu labourers to weed the crop well. A larger maize harvest will result. Pay attention to the general soil texture of the maize field Soil conditions affect the level of response to fertilizer. Soil texture serves as an important indicator of several soil characteristics which affect the level of maize yield response to fertilizer, and so affect the profitability of using fertilizer. Light-textured or sandy soils
17 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 17 typically are less fertile than medium-textured soils (loams and clays), so respond well to fertilizer when growing conditions are good. Medium-textured soils are not quite as responsive to fertilizer as light-textured soils, but they typically are less risky soils upon which to use fertilizer they are less affected by drought and fertilizer does not leach so readily from them under heavy rains. Consequently, medium-textured soils are the preferred soils for fertilizer use in most parts of Malawi. Which fertilizer to buy The area-specific fertilizer recommendations for hybrid maize are based upon the use of urea and 23:21:0+4S. A farmer with only a small amount of money will not be able to afford both. Which one should the farmer buy? In Malawi, if maize requires fertilizer, in the great majority of cases it requires nitrogen first of all. Researchers from Chitedze have shown this over and over. Phosphate and sulphur are important, but the main response in maize yield to the application of fertilizer comes from the nitrogen in the fertilizer, rather than from the other two nutrients. Consequently, a farmer who cannot purchase the entire recommended fertilizer package should use his or her limited cash to buy the fertilizer which provides the most nitrogen for the least cost. In Malawi at present, this fertilizer is urea. When applying only urea, the farmer should apply the fertilizer soon after emergence. If more than a bag of urea is applied, in order to avoid much of the fertilizer being leached washed out of the rooting zone of the soil or washed away by heavy rains, it is best to apply the fertilizer in split doses. That is, half of the fertilizer should be applied soon after emergence, with the remaining fertilizer being applied three to four weeks later. Applying nitrogen alone is not the best way of managing soil fertility for maize, and should be seen only as a short term strategy for farmers. If the farmer applies only nitrogen alone every year for several years, eventually sulphur and phosphorus deficiencies will begin to reduce maize yields. As a rough guideline, farmers should apply 23:21:0+4S or another fertilizer containing phosphate and sulphur every two or three years if using only nitrogen in other years. Kasungu, Mzimba, and Chitipa are known as areas in which phosphorus deficiencies are more common than elsewhere, so in those areas farmers should apply phosphate and sulphur every other year. Nitrogen sources Fertilizer prices change. The other main nitrogen-containing fertilizers which smallholders might use in Malawi are Calcium Ammonium Nitrate (CAN) and Ammonium Sulphate (AS, also called Sulphate of Ammonia). In the future possibly one of these fertilizers or some other fertilizer may become a cheaper source of nitrogen than the urea used in these
18 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 18 recommendations. In order to be able to determine whether this might be the case, farmers should know how to compare fertilizers in terms of the cost of the nitrogen they supply: Per bag, the two other fertilizers are cheaper than urea: CAN sold for about MK 695 per bag and AS for about MK 620 per bag in 1998/99, versus MK 840 for urea. However, urea contains more nitrogen. Urea has 46% nitrogen, the best CAN contains 28% nitrogen, and AS has 21% nitrogen. The nitrogen content of the fertilizer is usually printed on the fertilizer bag. A 50 kg bag of urea will contain 23 kg of nitrogen, a bag of CAN will contain 14 kg of nitrogen, and a bag of AS will contain 11.5 kg of nitrogen. To calculate the price of one kg of nitrogen from the different sources, you divide the price of a bag of fertilizer by the number of kg of nitrogen it contains. The cost of one kg of nitrogen in 1998/99 as urea was MK = MK 36.52, as CAN the nitrogen cost MK = MK 49.64, and as AS it was MK = MK At current prices, urea is the cheapest fertilizer nitrogen for your maize. However, many farmers prefer using CAN or AS to urea. Urea requires more care in its use than do the other two fertilizers. Urea is more likely to damage the plant if placed too close to the roots, and it must be covered with soil. Moreover, farmers can see maize plants respond to the application of CAN or AS within a shorter period of time than is the case when urea is applied. However, farmers need to be aware of the additional cost they face using CAN or AS rather than urea. Knowing this, likely farmers would be willing to buy urea and be a bit more careful in using it, rather than buying the more expensive nitrogen of CAN or AS. Where should limited amounts of fertilizer be applied on the field? Most farmers in Malawi do not have homogeneous fields. Rather, the soil varies from place to place in a field. Ant-hills, termites, or kaufiti (Striga) may make it difficult to grow maize in some corners of the maize plot, while maize does well elsewhere. If a farmer only has a limited amount of fertilizer, should he or she apply it to all parts of the field equally? No, one should be selective in deciding which parts of the field receive fertilizer. The best and the worst parts of the field should not receive fertilizer. By the best parts of the field we mean the most fertile parts. Several areas of the country have soils which are inherently very fertile - the heavier soils on the floodplains of the Lakeshore and the Lower Shire Valley. Other areas of the country have small pockets of very rich soil, particularly near dambos. Sometimes a field will have a patch of good soil which, even without fertilizer, produces maize which is dark green in colour, full grown, and with large cobs. This patch might have been where a cattle khola had been located or where a family formerly lived. Whether such fertile areas are small patches within a field or full fields, farmers shouldn t put fertilizer on them. Such soils are not very responsive to fertilizer. The sale of the additional
19 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 19 maize which the fertilizer will provide from these patches will not be sufficient to pay for the fertilizer applied to the maize there. The worst parts of the field are those in which maize rarely does well. Adding fertilizer to those parts usually will not change the situation and bring good maize harvests. The reason those patches of the field do not provide any maize harvest likely is not because of poor soil fertility, but some other problem. Kaufiti infestation may lead to no maize harvest. Termites may destroy the crop year after year in that portion of the field. There may be some soil pest that kills the maize. Waterlogging may prevent the crop from thriving. Fertilizer likely will not solve the problems of poor production in these areas of the field. Do not waste fertilizer on them. It would be better to grow a different crop than maize on these patches. Grain legumes groundnut, pigeonpea, soybean, Bambara groundnut, and others particularly would be a good alternative crop, as they reduce kaufiti and, if the residues are incorporated in the soil, will improve the fertility and physical properties of such soils. Moreover the grain yield of these legumes will likely exceed that of unfertilized maize on such sites. As a general rule, apply fertilizer to those parts of the field where you can get a harvest of maize, however small, without applying fertilizer. If you can get at least a small harvest of maize off of the particular area of your field without fertilizer, you can quite confidently apply fertilizer to that area and expect to get a higher yield. The fact that you get a harvest at all means that maize can grow there a pest or some other problem is not absolutely preventing maize growth. Poor soil fertility is more than likely the reason the crop yield was small. If so, fertilizer will address that problem. What amount of fertilizer should be applied on the field? The question then arises as to how a limited amount of fertilizer should be distributed over the field. The farmer has two options: a) Should one apply the fertilizer thickly over a small area of the field at the recommended rate of application?, or b) Should he or she spread the fertilizer thinly over a much larger area of the maize field at a rate significantly less than the recommended rate? The farmer should spread the fertilizer thinly at a rate lower than the recommended rate. Recall two points from the discussion above. The first is the law of diminishing returns every additional kg of fertilizer you apply to a maize field will result in a slightly lower amount of maize yield in response. Take a look back at Table 1. You get more maize for every kilogram of fertilizer applied at lower rates of application than at higher rates.
20 AREA-SPECIFIC FERTILIZER RECOMMENDATIONS FOR MAIZE - PAGE 20 The second point is that the recommendations made in the two basic recommendations maps are to be seen as maximums. Lower rates of fertilizer application than those indicated do provide farmers with a good return. No one should see the recommendations as the only rate of fertilizer to use. Lower rates make sense. So, for example, if the recommendation for your area and production aim is 69:21:0+4S, but you only have enough fertilizer to apply that amount to half of the area of your field on which it is worthwhile to apply fertilizer, it would be better to apply half of the recommended rate over the entire area. Your maize yield at the end of the season will be higher by doing so than if you applied the fertilizer to half of the field and nothing to the other half. Of course, the farmer should use common sense in so doing. Below a certain level of fertilizer application not much less than a rate of one bag of fertilizer per hectare it becomes very difficult to apply the small amount of fertilizer evenly. In such cases, the farmer should consider fertilizing those higher-potential parts of his or her field which require fertilizer at a low, but manageable rate, and planting a different crop altogether on the remainder of the field for which there is insufficient fertilizer. The best crop for the unfertilized portion would be one of the grain legumes groundnut, pigeonpea, soybean, or Bambara groundnut. Use organic sources of fertility Finally, inorganic fertilizer is not the only source of nutrients which farmers can apply to their maize. Organic sources should be made use of if available. By organic sources, we mean grain legume crop residues, khola manure of good quality, compost, and prunings from nitrogen fixing shrubs and trees. Use of all of these will increase the nutrient content and improve the physical condition of the soil. However, you should pay attention to the quality of the organic material. You want material that has a good amount of nitrogen and will rot relatively quickly when put in the soil. Maize stover is not very suitable. It has very little nitrogen and does not rot very quickly. The residues from nitrogen-fixing legumes are a much better choice of organic materials to put in the soil. The farmer should consider putting into rotation with maize a crop of a grain legume, such as groundnuts or soybean. Of all of the nitrogen-fixing legume crops in Malawi, velvet bean (kalongonda) provides the greatest amount of nitrogen-rich residue for building the fertility of the soil. If the kalongonda residues are incorporated into the soil after harvest, a rotation with velvet bean will lead to higher maize yields. Intercrops are also useful, although they will not give as much organic material as will rotations. Pigeonpea, particularly, is a good intercrop with maize. Prunings from agro-forestry plants should also be used. Discourage farmers from burning residues from leguminous crops. In reality, they are burning good fertilizer when they do. It is foolish to do so.