Performance of sugarcane varieties with contrasting growth habit in different row spacings and configurations

Controlled traffic (matching wheel and row spacing) is being widely adopted in the Australian sugar industry to minimise the adverse effect of soil compaction caused by heavy machinery such as cane harvesters and haul-outs. In this study, the performance of current cane varieties with contrasting growth habits in differing row spacings and planting arrangements designed to achieve controlled traffic outcomes is reported. The study was conducted on an irrigated site in the Farnsfield district of the Isis mill area. Cane varieties Q138, Q188A, Q205A and Q222A were planted with whole stick, conventional mouldboard opener planters in 1.5 m and 1.8 m single rows and in dual rows on 1.8 m or 2.0 m centres, as well as by billet planting in a 1.8 m wide throat system. Shoot counts and biomass samples were collected at intervals during the growing season. There were no significant differences in cane yields, ccs or sugar yields between row spacings at harvest, and nor was there any significant interaction between varieties and row spacings for any parameter. This was despite there being significantly fewer harvested stalks in 1.8 m single rows (8.2/m2) and 1.8 m wide throat (9.3/m2) than in standard 1.5 m single rows (10.2/m2) or the 1.8 m (10.6/m2) and 2.0 m (10.3/m2) dual row spacings. Much heavier individual stalk weights recorded in the 1.8 m single and wide throat billet plantings were able to compensate for lower stalk numbers. Results confirm the relative insensitivity of cane yields to crop row spacing and suggest considerable flexibility in developing row spacings to suit controlled traffic farming systems. There were significant differences between varieties in cane yields, ccs and sugar yields. Cane yields for Q205A and Q222A (124 t/ha and 121 t/ha) were significantly higher than Q188A (115 t/ha) and Q138 (112 t/ha). However, in terms of sugar yield, these cane yield differences were modified to some extent by variation in ccs, with Q222A and Q188A (13.8% and 13.5%, respectively) having higher CCS than Q205A (12.9%) and Q138 (11.1%). The combined effects resulted in the highest sugar yields in Q222A (16.8 t/ha), with Q205A and Q188A (15.8 and 15.5 t/ha, respectively) out yielding Q138 (12.7 t/ha). Varieties used different strategies to achieve final cane yields, with high final stalk numbers in Q138 (10.5/m2) and low stalk numbers in Q188A (9.0/m2) compensated for by differences in individual stalk weights

Managing yield decline in sugarcane cropping systems

This paper summarises the results from ten years of yield decline research carried out by the Sugar Yield Decline Joint Venture in the Australian sugar industry. The research concludes that, although the ultimate expression of yield decline may be through adverse effects of pathogens on sugarcane root systems, yield decline is a complex issue caused by a number of factors being out of balance in the sugarcane cropping system. Soil degradation has been the result of the long-term sugarcane monoculture and how it has been practiced. Specific research has shown that the long-term monoculture, uncontrolled traffic from heavy machinery and excessive tillage along with practices that deplete organic matter all contribute to yield decline. It is argued that changes to the cropping system that will conserve organic matter, break the monoculture, control traffic and minimize tillage are the most appropriate ways to combat yield decline. The technology is now available to incorporate these changes into the cropping system and a more sustainable, profitable and environmentally responsible cropping system is proposed. The proposed system is not prescriptive and many acceptable variations will be just as suitable providing the basic principles of organic matter conservation, breaking the monoculture, controlling traffic and minimizing tillage are no compromised

Review of Productivity Trends in the Herbert Sugarcane Growing Region

This review was initiated by the Herbert Cane Productivity Services (HCPSL) limited in order to identify the major reasons for highly variable productivity in recent years. The review encompassed the collation and analysis of productivity data held by HCPSL, interpretation of the analyses, and interviews with growers. In general the outcomes clearly indicated that water management (seasonal conditions, drainage, water logging), various aspects of harvesting (groups too big, harvesting too fast, not enough adjustment for seasonal conditions/ geographic harvesting, cane loss) and season length (the harvest season being too long) were the main factors influencing productivity in the Herbert. Suggestions are made as to how these issues may be addressed. Although it is acknowledged that varieties are an important part of any production system it is demonstrated that their influence on the large season to season variability in productivity is relatively minor.\ud \ud The following recommendations are made:\ud \ud Recommendation 1: The large amount of variety performance data on different soil types in different seasons held by HCPSL warrants collation and analysis in order to objectively assess whether different varieties are suited to different soil types and regions.\ud \ud Recommendation 2: The importance of seasonal conditions in November as they affect the subsequent crop needs to be fully appreciated and strategies adopted to minimise their impact.\ud \ud Recommendation 3: The difference in climatic regimes between the Ingham Line area (and Upper Stone) and other areas needs to be recognised and if necessary different production strategies put in place.\ud \ud Recommendation 4: The most suitable varieties for Ingham Line may well be different to those for other areas and this should be taken into account within the variety evaluation program\ud \ud Recommendation 5: Emphasis should be placed on the development of mound planting for the wetter areas.\ud \ud Recommendation 6: The analysis of harvesting losses in the current crop and harvesting practices on the productivity of the next crop needs to be continued and expanded. It is a critical area of investigation.\ud \ud Recommendation 7: The harvest season should be adjusted to aim for the crushing to finish by the end of October with the current practice of setting a starting date to be replaced by setting a finishing date. This recommendation will obviously require an earlier starting date and probably staggered harvesting based on geographical and equity considerations but should not be dismissed out of hand

The value of legume breaks to the sugarcane cropping system - cumulative yields for the next cycle, potential cash returns from the legume, and duration of the break effect

In rotation experiments conducted in Australia over the past decade, it has been demonstrated that breaking the sugarcane monoculture between cycles with another species improves sugarcane yields by 20–30% in the plant crop due largely to improvement in soil health. However, to break the sugarcane monoculture, it is necessary to forego at least one cane harvest and many growers are concerned that will jeopardise economic viability. To test this, several of the rotation experiments were carried through to second and third ratoons and the cumulative cane and sugar yields were measured over the crop cycle. The response to breaks in the ratoons was similar to those measured in the plant crop and there were clear indications that over a crop cycle the inclusion of a short-term (6–9 month) legume break would be economically viable. In general, the persistence of yield benefits into the ratoons resulted in cumulative sugar yields over a plant and four ratoons covering the loss of the one cane harvest when the break was included. In two other experiments, sugarcane that had been planted after breaks was removed, following a plant crop in one instance and a plant and two ratoons in the other, and plots were immediately replanted to sugarcane. The yields of the subsequent plant crop were no better than those with long-term sugarcane monoculture, indicating that the break effect per se was short-lived. Thus the longevity of the yield response into later ratoons appears to be largely associated with very positive effects of the break on the immediate plant crop. These findings strongly support the regular inclusion of rotation breaks in the sugarcane cropping system, a strategy that is especially attractive when there are suitable break species like soybeans and peanuts that can be harvested as cash crops. Harvesting these break crops does not detract from the break effect while further improving overall grower profitability

Reduced tillage planting and the long-term effect on soil-borne disease and yield of sugarcane (Saccharum inter-specific hybrid) in Queensland, Australia

Pachymetra is a major root disease of sugarcane causing yield and economic loss in the Australian sugar industry, with planting of resistant cultivars being the control strategy practiced by the industry. To adopt reduced tillage and not be affected by soil compaction in the old inter-row it is necessary to re-plant into the old crop row. The hypothesis was: would reduced tillage and planting in the old crop row in conjunction with rotation of resistant and susceptible cultivars minimise the effect of this soil borne disease on crop yield? To facilitate the adoption of reduced tillage in the Australian sugar industry randomized block field experiments were undertaken on Alfisols, near Tully, north Queensland and Bundaberg, south Queensland, Australia comparing reduced tillage with conventional cultivation for planting sugarcane Results showed that, providing Pachymetra resistant cultivars were used, there was no yield reduction with reduced tillage. Levels of Pachymetra remained close to the threshold of 40,000 spores per kilogram of soil under the resistant cultivar but increased under the susceptible cultivar as the crop cycle progressed. Planting a resistant cultivar after a susceptible cultivar or vice versa did not affect cane yield. Over a crop cycle of a plant and three ratoons at Bundaberg the average yields of the susceptible and resistant cultivars were 114 and 89 t/ha, respectively, an increase of 28% with the resistant cultivar. Similarly at Tully the average yield for the resistant and susceptible cultivar was 75 and 69 t/ha, a 9% increase in yield with the resistant cultivar.\ud \ud Earthworm numbers recovered quicker under reduced tillage compared with conventional tillage suggesting that in the medium to long-term soil health will benefit by the adoption of reduced tillage for planting sugarcane. Reduced tillage did not affect the population of Pratylenchus zeae and increased the number of Rotylenchus nematodes under stool sprayout compared with all other tillage treatments.\ud \ud It is concluded that sugarcane cultivars are available that allow the adoption of reduced tillage in Pachymetra areas without compromising yield

Techniques for improving establishment of maize and soybean on cracking clay soils in the Burdekin River Irrigation Area

Emergence of irrigated row crops is a problem on heavy clay soils in the Burdekin River Irrigation Area (BRIA). Two field trials were conducted on laser levelled land to examine the effects of sowing into ridges and beds, using before and after sowing irrigation and different opener-press wheel combinations on the emergence of maize and soybean. There was no difference between beds and ridges on establishment of both crops. Establishment of maize was a mean of 63.4% and soybean was a mean of 35.4% across all treatments. After sowing irrigation was superior to before sowing irrigation for the establishment of both maize and soybeans. Maize gave 76.5% and 50.2% for after sowing and before sowing irrigations, and soybean 45.2% and 25.5% respectively. The results suggest that the best option for improving maize and soybean establishment on the heavy clay soils of the BRIA is to use after sowing irrigation with spear point-split steel press wheels on laser levelled ground with a well aggregated seedbed consisting of less than 10% fine (<1 mm) material

High input sugarcane production systems can mask the adverse effects of poor soil health

Breaking the sugarcane monoculture or fumigating long-term sugarcane land enhances crop establishment. In many situations, enhanced establishment is instrumental in ultimately producing higher cane and sugar yields. However, recent studies in rotation experiments in the Burdekin have shown that with full irrigation and high inputs of nitrogen fertiliser, tillering can be increased to the extent that poor primary shoot establishment can be compensated by the production of more tillers. This results in the ultimate yield difference between breaks/fumigation and sugarcane monoculture being substantially reduced. The relatively good yields that can be produced with sugarcane monoculture in the Burdekin has led to a general conclusion that yield decline (poor soil health) is not an important issue in this region. However, research by the SYDJV has shown that soil health is as much an issue in the Burdekin as anywhere else, but the ultimate effect on crop yield can be masked by irrigation and high inputs of nitrogen fertiliser. The results of this research emphasise several important implications associated with management of high input systems. Although the adverse effects of poor soil health can be masked, the long-term consequences of ignoring soil health need to be seriously considered. Further, the excessive use of resources such as nitrogen fertiliser and irrigation water, have both economic and environmental consequences. In this paper we demonstrate that yields can be maintained with lower inputs in situations where soil health has been maintained through rotation breaks and the build-up of soil carbon (organic matter) levels. Further, it is argued that substituting high inputs to mask the effects of poor soil health is very much against the development of more sustainable sugarcane farming systems

Effect of breaks on sugarcane growth: relations between glasshouse and field studies

The effects of varying types and duration of breaks (other crops, pastures or bare fallows) and soil fumigation on subsequent growth of sugarcane crops were investigated in a series of five field experiments in Australia. Results from the first series of test plantings have shown breaks can produce significant effects on sugarcane growth and yield - at least as large as those from soil fumigation. These responses have generally been characterised by marked differences in shoot establishment and early growth in the first 70-90 days. Glasshouse studies conducted using soil from the same sites showed significant (P<0.05) effects of break history on early shoot growth (35-45 days) at four of the five sites. Positive responses to soil fumigation were also recorded at three of the five sites. Fumigation with methyl bromide produced minimal effects on early growth in soil that had been bare fallowed (-15% to 2%), or soil that had been fumigated in the field (-4% to 29%). Fumigation of soil from continuous cane treatments typically increased early cane growth by 25-30%. Most breaks had effects intermediate between the control and the bare fallow - both in early growth and response to fumigation. Shoot dry matter in unfumigated soil in the short-term glasshouse studies was strongly correlated with field shoot numbers at 70-90 days after planting and with dry matter production after 8 months. Correlations were either much weaker, or had disappeared entirely, by final harvest due to unexplained differences in growth rates among treatments during the final 4 months. Growth in fumigated break soil in the glasshouse was not correlated significantly with growth in the field, indicating that biotic factors were associated with these early growth differences in the field. These findings suggest that short duration pot experiments may be a useful research tool to study the biotic effects on early growth of sugarcane. This will provide more rapid experimental cycles and significant cost savings compared to field studies. However, other evidence suggests that results from such studies will not necessarily be a good indicator of ultimate crop yield