Ebook Integrated nutrient management for sustainable crop production: Part 2

Continued part 1, part 2 of ebook Integrated nutrient management for sustainable crop production provide readers with content about: integrated nutrient management - experience and concepts from New Zealand; integrated nutrient management - experience from South Asia; integrated nutrient management - experience from China; integrated nutrient management - experience from rice-based systems in Southeast Asia; integrated nutrient management - experience from South America;...

Chapter Integrated Experience and Nutrient Concepts from Management: New Zealand Experience and Concepts from New Zealand Antony H C Roberts Tony J van der Weerden Douglas C Edmeades INTRODUCTION New Zealand’s land-based animal and crop production need to be conducted in a manner that is both economically and environmentally sustainable Soil fertility management on pastoral farms, now and in the future, revolves around supplying the quantity and quality of pasture and forage crops to suit the requirements for animal production and health, and limit avoidable environmental degradation The legume is critical to pastoral farming in that it supplies the most deficient plant nutrient, that is, nitrogen (N), through biological fixation, as well as providing high quality forage for animals Similarly, a full understanding of arable crop requirements, and the impact of cultural practices on soil and water quality are required to develop an integrated nutrient management (INM) program Agriculture is under scrutiny because of its impact on soil condition and contamination, water quality, and biodiversity These resource management issues will also impact the profitability of New Zealand agriculture, and the long-term marketing of produce, thus giving land managers a strong incentive to adopt or develop solutions to these issues 253 © 2008 by The Haworth Press, Taylor & Francis Group 254 Integrated Nutrient Management for Sustainable Crop Production This chapter briefly discusses agricultural production in New Zealand, issues surrounding fertilizer use, agricultural sustainability, and environmental concerns The extent to which nutrient management is integrated in New Zealand agriculture, and the soil and nutrient management tools developed and implemented over the last ten years are discussed including case studies Emerging issues and research gaps are identified MAJOR SOIL AND CLIMATIC REGIONS AND MAJOR CROPPING SYSTEMS New Zealand lies to the southwest of Australia in the Pacific Ocean It consists of three major islands, which stretch some 1,600 km, over 14 degrees of latitude The three islands embrace such climatic extremes as subtropical Northland, the cold uplands of the Alpine regions, the semiarid basins of Central Otago, and the very wet mountains and lowlands of Westland The topography is varied, with around 50 percent being steep, 20 percent moderately hilly, and less than 33 percent is either rolling or flat (Taylor and Pohlen 1968) The sharp relief of the islands is sufficient to produce a significant range of temperature from north to south and with altitude Mean air temperatures at sea level are approximately 158C in the north, 128C in the center (about Cook Straight), and 9.58C in the south, and these fall by about 1.58C for each 305 m of elevation The prevailing westerly winds are forced up and sideways by the mountain ranges, causing those areas directly exposed to the westerly airstreams, and of higher altitudes to have the greatest rainfall This tendency for wetness in the west and dryness in the east is most extreme in the southern South Island, where more than 5,000 mm of rain falls on the western-southern Alps, compared to less than 500 mm in the Central Otago basin on the eastern side (Taylor and Pohlen, 1968) The geology underlying the soil mantle varies in texture and composition and includes igneous rocks ranging from ultrabasic to acidic (e.g., basalt, andesites, and rhyolite), metamorphic rocks, and sedimentary rocks (e.g., conglomerates, sandstones, mudstones, and limestones) Based on their parent materials, the soils of New Zealand may be broadly classified into three major “groups”: sedimentary (sandstone, siltstone, and mudstone), ash (andesite, basalt), and pumice (rhyolite) soils (Roberts and Morton, 1999) Sedimentary soils include the following soil orders: brown, sands, gley, melanic, pallic, recent, semiarid, and most ultic soils Ash soils include the allophanic and granular orders, and most oxidic soil, while pumice soils are composed of the pumice soil order © 2008 by The Haworth Press, Taylor & Francis Group Experience and Concepts from New Zealand 255 New Zealand’s largest industries are concerned with biomass production, and processing, and 60-70 percent of export earnings derive from these industries Agriculture is at the forefront of these industries Annual agricultural production in 2001/2002 was worth $16.61 billion Pastoral farming, based primarily on grass/legume pastures, is the dominant enterprise with 13.5 Mha in pasture Some 39 m sheep and 4.5 million cattle are wintered on around 33,101 properties (Meat and Wool Innovation April 2003), and million dairy cattle are carried on 12,751 properties (LIC Dairy Statistics 2003/04) In addition, there are 2,115 deer farms (NZ Statistics Department, 1993) Arable crop production in New Zealand covers approximately 300,000 hectares (ha) of land cultivated for arable and vegetable crops, with the concentration of cropping activity occurring in Canterbury The main crops grown are wheat, barley, oats, peas, maize, grass and clover seeds, potatoes, sweetcorn, and onions (Williams, 1998) These are typically grown as part of a mixed cropping rotation, where land is rotated between cropping and pasture phases, and the latter may be utilized for either seed production or grazing In terms of INM, the country’s critically important production agriculture focuses on meeting crop and animal nutrient requirements by applying nutrients that are deficient, or unavailable from natural soil reserves, as multinutrient fertilizer materials in order to maximize the quantity and quality of the harvested product Most fertilizer nutrients used in New Zealand are supplied using imported raw materials for example, phosphate rock and elemental sulfur, to manufacture single superphosphate or by importing already manufactured compound fertilizers, for example, diammonium phosphate (DAP) and urea Given that increasing, or even just maintaining, the current soil nutrient status requires more nutrients imported than amounts exported in products, New Zealand agriculture will always be a net sink for imported nutrients, at current production levels Therefore, New Zealand agriculture can only be as sustainable as the capacity of the earth to continue to supply fertilizer raw materials AGRICULTURAL PRODUCTION AND NUTRIENT BALANCES Globally, continual agricultural technology development has allowed greater production from the same land area (Isherwood, 1998; Lomburg 2001; Borlaug 2003) The same is true for New Zealand For example, over the past forty years to the mid-1990s, land under cultivation has declined by © 2008 by The Haworth Press, Taylor & Francis Group 256 Integrated Nutrient Management for Sustainable Crop Production percent to 16.6 Mha, of which 13.5 Mha is in pasture (Whittington, 1995) Yet, during this time, production has increased as follows (Anonymous, 1998): • the number of grazing animals (sheep, dairy, beef, pig, deer, and goat) by 58 percent to 58 million • wool production by percent to 197,000 tonnes (t) per annum • meat production by 71 percent to 1.8 million tonnes (Mt) per annum • dairy production by 131 percent to 10.65 million liters per annum • crop production by 58 percent to 950,000 t per annum More recent detailed major agricultural production outputs and national fertilizer sales since 1993/1994 (Table 6.1) show a trend for increasing productivity from the same land area but declining livestock numbers which can be attributed to increasing production efficiency Production in the dairy sector has approximately doubled since 1990, while wheat production has increased by 50 percent Beef numbers have remained constant while sheep numbers have declined by 40 percent Estimated macronutrient fertilizer sales for New Zealand are also shown (Table 6.1) Phosphate fertilizer sales have doubled while N fertilizer inputs have increased by approximately 400 percent since 1990 Much of this increase is presumably associated with the doubling in dairy production, although increased production of arable and vegetable crops and lamb meat also influences the fertilizer sales On a national basis, fertilizer nutrient imports into the country exceed the export of nutrients in finished products due mainly to the fact that a proportion of the fertilizer nutrients applied remains on the farm, or is lost via leaching runoff, or transfer to nonproductive areas This is consistent with the fact that some nutrients are accumulating under some farm types and soil groups, as discussed later However, while fertilizers are usually the most dominant source on nutrients entering the farm, they are not the only ones On some soils, nutrients are released (weathered) from soil minerals, for example, K and P, and some nutrients come from rainfall, for example, S and N, especially if the farm is close to the coast Irrigation water, farm dairy effluent, organic manures, and supplementary feed are other sources of nutrients to the farm Nutrient balances are useful tools to assist in developing a profitable and sustainable nutrient management program, providing they take account of all inputs and outputs A recent examination, using national agricultural statistics, with a computerized nutrient budget program OVERSEER Nutrient Budgets 2, highlights some interesting points © 2008 by The Haworth Press, Taylor & Francis Group TABLE 6.1 New Zealand fertilizer sales (NPK only), livestock numbers, milksolids production, and wheat grain production since 1993/1994 Year 1993/ 1994 1994/ 1995 50,298 49,466 No sheepa (000) 4,758 5,048 No cattlea (000) b No dairy cattle (000) 3,550 3,839 736 733 Tonnes milksolidsb (000) Tonnes Wheat (000) 2,419 2,452 Tonnes Barley (000) 3,955 3,028 1,057 1,256 Tonnes Nc (000) 1,690 1,700 Tonnes Pc (000) 1,127 1,121 Tonnes Kc (000) 1995/ 1996 1999/ 2000 2000/ 2001 2001/ 2002 48,816 47,349 46,077 44,400 44,190 5,183 4,852 4,775 4,379 4,283 4,090 4,165 4,398 4,516 4,543 788 880 893 880 981 42,260 4,276 4,794 1,096 40,033 39,546 4,345 4,495 5,038 4,495 1,152 1,191 2,770 3,672 1,555 1,706 1,157 1996/ 1997 NC NC 1,400 1,694 1,121 1997/ 1998 NC NC 1,389 1,668 1,077 1998/ 1999 NC NC 1,535 1,668 1,096 Note: NC = data not collected a Meat and Wool New Zealand Farm Statistics b Livestock Improvement Corporation Dairy Statistics 1998-99 and 2003-04 c New Zealand Fertiliser Manufacturer's Association Statistics 257 © 2008 by The Haworth Press, Taylor & Francis Group NC NC 1,800 1,773 1,104 NC NC 2,307 2,009 1,041 3,015 4,409 2,691 2,113 1,160 2002/ 2003 3,203 3,783 3,230 2,081 1,344 2003/ 2004 39,688 4,614 4,614 1,254 2,710 2,980 3,480 2,177 1,328 258 Integrated Nutrient Management for Sustainable Crop Production Dairy Farm Nutrient Budgets Nine regions represent about 80 percent of the total dairy industry with respect to total area and number of cows Estimated nutrient balances as determined by OVERSEER for each region and nutrient are given in Table 6.2 The inputs are based on current typical fertilizer inputs used by farmers within their respective regions, and therefore the predicted balances are representative of current practice These results suggest that inputs of phosphate (P), potassium (K), and calcium (Ca) exceed the losses of these nutrients under dairying in all regions The average positive balances are 19, 37, and 196 kg ha21 year for P, K, and Ca, respectively In contrast, four regions are in negative balance for magnesium (Mg), namely Taranaki, South Auckland, West Coast, and Bay of Plenty (Table 6.2) These same four regions, together with the Central Plateau, Southland, and Northland, are in negative balance with respect to sodium (Na) While this will have no impact on pasture growth, declining soil Na levels could lead to sodium deficiency in milking cows Assuming that the soil fertility levels for the nutrients P, K, Ca, and Mg are optimum for pasture production (which will not always be the case), then it could be TABLE 6.2 Dairy farm nutrient balances (inputs from all sources minus outputs from all sources) for each nutrient and region Nutrient balances (kg nutrient/ha/year21) Region N P K S Ca Mg Na Northland South Auckland Bay of Plenty Central Plateau Taranaki Wairarapa North Canterbury West Coast Southland 0 0 0 0 26 16 13 13 23 27 23 43 39 33 31 45 18 43 42 37 0 0 0 0 206 155 204 209 164 165 230 237 196 219 22 16 223 10 216 210 233 250 271 244 25 225 225 Source: D.C Edmeades, unpublished data Note: For N and S the models are constrained such that the balance is always zero In the case of N, any deficit of N is balanced by an increase in symbiotic N from clover, and for S, any surplus is assumed to be leached © 2008 by The Haworth Press, Taylor & Francis Group Experience and Concepts from New Zealand 259 expected that soil test levels for P, K, and Ca are increasing and for Mg declining An analysis of around 250,000 advisory soil test levels between 1988 and 2001 (Wheeler et al., 2004) supports the nutrient balance in so far as Olsen P levels have increased in the dairy sector and Mg levels have slowly declined Sheep/Beef Farm Nutrient Budgets Nutrient balances were also derived for the sheep/beef farming sector for seven (of eight) of the farm Classes used by the Meat and Wool Board Economic Service, carrying 95 percent and 98 percent of all sheep and beef, respectively (Table 6.3), using the methodology described The balances were estimated using typical fertilizer inputs used by farmers within their respective regions and therefore are representative of current practice For P, all Classes are in a positive balance, except for the High Country (Class 1) of the South Island, noting that the positive balance for Class (Canterbury Finishing) is small The K balances are positive for all Classes despite the fact that significant fertilizer K is applied only on Class (Northland/Waikato Finishing) Except for the High Country, all Classes are in positive balance with respect to Ca Class (NI Intensive Finishing TABLE 6.3 Nutrient balances (kg nutrient/ha) for each nutrient and sheep/beef farm class Class N P K S Ca Mg Na 0 0 0 26 10 14 13 13 10 15 19 31 22 18 16 18 0 0 0 21 36 45 46 36 33 46 8 221 211 213 231 21 Source: D.C Edmeades, unpublished data Notes: Class 1: South Island High Country; Class 2: South Island Hill Country; Class 3: North Island Hard Hill Country; Class 4: North Island Hill Country; Class 5: North Island Intensive Finishing; Class 6: South Island Finishing/Breeding; Class 7: South Island Intensive Finishing For N and S the models are constrained such that the balance is always zero In the case of N, any deficit of N is balanced by an increase in symbiotic N from clover, and for S, any surplus is assumed to be leached © 2008 by The Haworth Press, Taylor & Francis Group 260 Integrated Nutrient Management for Sustainable Crop Production on volcanic soils) is in negative balance with respect to Mg, and Classes (NI East Coast), (Wanganui/Manawatu), and (NI Intensive Finishing) are in a negative balance with respect to Na (Table 6.3) The mostly positive P balances are consistent with the soil test summary data (Wheeler et al., 2004) that shows increasing soil Olsen P levels on sheep/ beef farms also Current soil K levels are within the biological optimal range even though no fertilizer K is being applied This is understandable given that sedimentary soils have significant reserve K (it is generally accepted that economically it is prudent to mine these soil K reserves), and sheep and beef cattle are more efficient recyclers of pasture K on the farm The exception is Class 5, where the current average soil K level for these mostly volcanic soils is also within the optimal range but is being achieved with significant fertilizer K inputs Current soil Mg levels on both sedimentary and volcanic soils are above the minimum level from optimal pasture production For most Classes there is a slight positive Mg balance suggesting that this situation can be sustained for some time Soil Mg reserves are sufficiently high on sedimentary soils to fully meet medium term needs, but the Class volcanic soils are in a negative balance indicating that they could become Mg deficient in time In New Zealand agriculture, very little nutrients are purposefully returned or added to the soil as organic nutrient sources In the grazed pasture situation, 80 to 90 percent of the nutrients animals ingest from forage are returned as dung and urine On dairy farms, dairy effluent is applied to a proportion of the farm, and small amounts of poultry manure (actually poultry manure and bedding material such as wood shavings) are applied to pastoral and cropping farms in close proximity to broiler and layer chicken facilities FERTILIZERS AND SUSTAINABLE DEVELOPMENT Pasture and Crop Productivity in New Zealand In order to increase or maintain both pasture and crop productivity, major elements are routinely applied (primarily nitrogen [N], phosphate [P], sulfur [S], and potassium [K]); soil pH is adjusted by the addition of lime (CaCO3) application and trace elements (usually cobalt [Co], copper [Cu], selenium [Se], boron [B], and/or molybdenum [Mo]) are applied to create a soil environment which encourages legume growth and function (biological N fixation), as well as forage with the required mineral content for animal health However, there are sixteen known essential elements for plant and animal health and production and not all are presently applied as fertilizer © 2008 by The Haworth Press, Taylor & Francis Group Experience and Concepts from New Zealand 261 or soil amendments Agriculture is depleting soil reserves of these nutrients through the net export of nutrients as product or as indirect soil losses To date, fertilizer recommendations for optimizing pasture production have been based on the premise that only those macronutrients that are deficient in soil are applied, typically N, P, K, and S Lime is applied as required to alter the soil pH and thus calcium (Ca), magnesium (Mg), and sodium (Na) are rarely recommended For this reason, currently, pastoral farming is for some regions and farming types a net exporter of these nutrients, as shown in Tables 6.2 and 6.3 This nutrient depletive philosophy is not sustainable and at some time in the future, soils will be unable to supply sufficient quantities of these essential nutrients (e.g., Ca, Mg, and Na and possibly some trace elements) to sustain high levels of pasture and animal production At present, it is not known how long our soils will continue to supply sufficient levels of these nutrients, and it is possible that consumer perception may determine that soil nutrient reserve depletion does not fit in with their concept of “sustainable agriculture.” It is possible then to surmise that future fertilizer nutrient requirements will include at least two additional essential cations, namely Ca and Mg Fortuitously, the prevalence of calcium phosphate fertilizer (single superphosphate) use in New Zealand pastoral agriculture has meant that sufficient Ca has been unconsciously added to replace losses, occurring particularly on well buffered soils where lime application has been sporadic In the early 1990s, a marked swing away from these “traditional” fertilizers to the use of high analysis NPK types (such as DAP) may have resulted in Ca depletion to the extent that animal production may have suffered Losses of Ca from dairy soils can be alarmingly high Recent work (Rajendram et al., 1998) has measured cation leaching (as a function of counterion movement due to nitrate leaching) under grazed dairy pastures Bearing in mind that this is representative of intensive dairying and leaching, measurements include, a very high drainage year, inputs of Ca are almost in balance with outputs, that is, 110 kg ha21 Ca (Figure 6.1) However, should a fertilizer be used which contains little or no Ca, then Ca depletion could be potentially quite large Edmeades and Perrott (2004) also concluded that New Zealand’s current farming practices are sustainable with respect to Ca, providing the use of superphosphate and lime continues There is little evidence of widespread application of Mg fertilizer to enhance pasture production or herbage Mg content (for animal requirements) The exception is on undeveloped pumice soils that may be deficient in Mg for grass/legume pasture growth Most soils are not deficient in Mg for pasture growth and so typically Mg does not form part of the fertilizer program Hypomagnesemia remains an issue in many areas, particularly before and © 2008 by The Haworth Press, Taylor & Francis Group 262 Integrated Nutrient Management for Sustainable Crop Production 600 kg super/ha year –1 Milk 15 Rain 130 Transfer 10 70 Leaching 100 FIGURE 6.1 Annual inputs and outputs of calcium (kg/ha) at the Dairying Research Corporation (DRC) No Dairy with no N fertilizer applied Source: S F Legard, unpublished data after calving or lambing Despite research showing Mg fertilizer as effective in preventing or reducing this metabolic disease (O’Connor et al., 1987), most farmers directly supplement their animals during risk periods As indicated in the pastoral nutrient budgets, Mg balances are frequently negative implying soil Mg reserves are declining In his review, Edmeades (2004) suggested that in the absence of fertilizer Mg inputs, current reserves of soil Mg will be sufficient for a further twenty years Sodium is not required for plant growth but is essential for optimal animal production Edmeades and O’Connor (2003) in a recent review identified the central regions of both Islands as becoming Na deficient for grazing animals and noted that it was likely the Na would become a regular fertilizer input in these regions in the next few decades Environmental Concerns: Grazed Pastures Phosphate runoff (surface water quality) and nitrate leaching (groundwater quality) are the two main issues relating to nutrient management under pastoral systems Phosphorus Unlike nitrate (NO 23 ) and sulphate (SO 24 ), P leaching is not an issue in New Zealand except for minor areas of unmineralized peat soils, and some highly weathered podzolized sedimentary soils under high rainfall, and with low phosphate retention This is because the binding capacity for P (phosphate retention) is much higher than other anions, and most New Zealand soils have a large P sorbing capacity due to large quantities of short-range order iron and aluminum compounds in soils (McLaren and Cameron, 1990) However, it has been estimated that 45 percent to 80 percent (McColl, 1982; Gregg et al., 1993) of P inputs to surface water arise from diffuse agricultural sources such as runoff © 2008 by The Haworth Press, Taylor & Francis Group ... 0 26 16 13 13 23 27 23 43 39 33 31 45 18 43 42 37 0 0 0 0 20 6 155 20 4 20 9 164 165 23 0 23 7 196 21 9 22 16 22 3 10 21 6 21 0 23 3 25 0 27 1 24 4 25 22 5 22 5 Source: D.C Edmeades, unpublished data Note: For. .. 4,409 2, 691 2, 113 1,160 20 02/ 20 03 3 ,20 3 3,783 3 ,23 0 2, 081 1,344 20 03/ 20 04 39,688 4,614 4,614 1 ,25 4 2, 710 2, 980 3,480 2, 177 1, 328 25 8 Integrated Nutrient Management for Sustainable Crop Production... 6.3 Nutrient balances (kg nutrient/ ha) for each nutrient and sheep/beef farm class Class N P K S Ca Mg Na 0 0 0 26 10 14 13 13 10 15 19 31 22 18 16 18 0 0 0 21 36 45 46 36 33 46 8 22 1 21 1 21 3 23 1